diff --git a/lib/browser.ts b/lib/browser.ts
index 81107a693..186d592e7 100644
--- a/lib/browser.ts
+++ b/lib/browser.ts
@@ -1,5 +1,5 @@
 import {BPClient} from 'blocking-proxy';
-import {ActionSequence, By, Capabilities, Command as WdCommand, FileDetector, ICommandName, Options, promise as wdpromise, Session, TargetLocator, TouchSequence, until, WebDriver, WebElement} from 'selenium-webdriver';
+import {ActionSequence, By, Capabilities, Command as WdCommand, FileDetector, ICommandName, Options, promise as wdpromise, Session, TargetLocator, TouchSequence, until, WebDriver, WebElement, WebElementPromise} from 'selenium-webdriver';
 import * as url from 'url';
 import {extend as extendWD, ExtendedWebDriver} from 'webdriver-js-extender';
 
@@ -34,87 +34,14 @@ for (let foo in require('selenium-webdriver')) {
   exports[foo] = require('selenium-webdriver')[foo];
 }
 
-// Explicitly define webdriver.WebDriver
-// TODO: extend WebDriver from selenium-webdriver typings
-export class AbstractWebDriver {
-  actions: () => ActionSequence;
-  call:
-      (fn: (...var_args: any[]) => any, opt_scope?: any,
-       ...var_args: any[]) => wdpromise.Promise<any>;
-  close: () => void;
-  controlFlow: () => wdpromise.ControlFlow;
-  executeScript: (script: string|Function, ...var_args: any[]) => wdpromise.Promise<any>;
-  executeAsyncScript: (script: string|Function, ...var_args: any[]) => wdpromise.Promise<any>;
-  getCapabilities: () => wdpromise.Promise<Capabilities>;
-  getCurrentUrl: () => wdpromise.Promise<string>;
-  getPageSource: () => wdpromise.Promise<string>;
-  getSession: () => wdpromise.Promise<Session>;
-  getTitle: () => wdpromise.Promise<string>;
-  getWindowHandle: () => wdpromise.Promise<string>;
-  getAllWindowHandles: () => wdpromise.Promise<string[]>;
-  manage: () => Options;
-  quit: () => void;
-  schedule: (command: WdCommand, description: string) => wdpromise.Promise<any>;
-  setFileDetector: (detector: FileDetector) => void;
-  sleep: (ms: number) => wdpromise.Promise<void>;
-  switchTo: () => TargetLocator;
-  takeScreenshot: () => wdpromise.Promise<any>;
-  touchActions: () => TouchSequence;
-  wait:
-      (condition: wdpromise.Promise<any>|until.Condition<any>|Function, opt_timeout?: number,
-       opt_message?: string) => wdpromise.Promise<any>;
-}
 
-export class AbstractExtendedWebDriver extends AbstractWebDriver {
-  getNetworkConnection: () => wdpromise.Promise<0|1|2|3|4|5|6|7>;
-  setNetworkConnection:
-      (typeOrAirplaneMode: 0|1|2|3|4|5|6|7|boolean, wifi?: boolean,
-       data?: boolean) => wdpromise.Promise<void>;
-  toggleAirplaneMode: () => wdpromise.Promise<void>;
-  toggleWiFi: () => wdpromise.Promise<void>;
-  toggleData: () => wdpromise.Promise<void>;
-  toggleLocationServices: () => wdpromise.Promise<void>;
-  getGeolocation: () => wdpromise.Promise<{latitude: number, longitude: number, altitude: number}>;
-  setGeolocation:
-      (latitude?: number, longitude?: number, altitude?: number) => wdpromise.Promise<void>;
-  getCurrentDeviceActivity: () => wdpromise.Promise<string>;
-  startDeviceActivity:
-      (appPackage: string, appActivity: string, appWaitPackage?: string,
-       appWaitActivity?: string) => wdpromise.Promise<void>;
-  getAppiumSettings: () => wdpromise.Promise<{[name: string]: any}>;
-  setAppiumSettings: (settings: {[name: string]: any}) => wdpromise.Promise<void>;
-  getCurrentContext: () => wdpromise.Promise<string>;
-  selectContext: (name: string) => wdpromise.Promise<void>;
-  listContexts: () => wdpromise.Promise<string[]>;
-  getScreenOrientation: () => wdpromise.Promise<'LANDSCAPE'|'PORTRAIT'>;
-  setScreenOrientation: (orientation: string) => wdpromise.Promise<void>;
-  isDeviceLocked: () => wdpromise.Promise<boolean>;
-  lockDevice: (delay?: number) => wdpromise.Promise<void>;
-  unlockDevice: () => wdpromise.Promise<void>;
-  installApp: (appPath: string) => wdpromise.Promise<void>;
-  isAppInstalled: (bundleId: string) => wdpromise.Promise<boolean>;
-  removeApp: (appId: string) => wdpromise.Promise<void>;
-  pullFileFromDevice: (path: string) => wdpromise.Promise<string>;
-  pullFolderFromDevice: (path: string) => wdpromise.Promise<any>;
-  pushFileToDevice: (path: string, base64Data: string) => wdpromise.Promise<void>;
-  uploadFile: (base64Data: string) => wdpromise.Promise<void>;
-  switchToParentFrame: () => wdpromise.Promise<void>;
-  fullscreen: () => wdpromise.Promise<void>;
-  sendAppToBackground: (delay?: number) => wdpromise.Promise<void>;
-  closeApp: () => wdpromise.Promise<void>;
-  getAppStrings: (language?: string) => wdpromise.Promise<string[]>;
-  launchSession: () => wdpromise.Promise<void>;
-  resetApp: () => wdpromise.Promise<void>;
-  hideSoftKeyboard:
-      (strategy?: 'default'|'tapOutside'|'tapOut'|'swipeDown'|'pressKey'|'press',
-       key?: string) => wdpromise.Promise<void>;
-  getDeviceTime: () => wdpromise.Promise<string>;
-  openDeviceNotifications: () => wdpromise.Promise<void>;
-  rotationGesture:
-      (x?: number, y?: number, duration?: number, rotation?: number,
-       touchCount?: 1|2|3|4|5) => wdpromise.Promise<void>;
-  shakeDevice: () => wdpromise.Promise<void>;
-}
+// Explicitly define types for webdriver.WebDriver and ExtendedWebDriver.
+// We do this because we use composition over inheritance to implement polymorphism, and therefore
+// we don't want to inherit WebDriver's constructor.
+export class AbstractWebDriver {}
+export interface AbstractWebDriver extends WebDriver {}
+export class AbstractExtendedWebDriver extends AbstractWebDriver {}
+export interface AbstractExtendedWebDriver extends ExtendedWebDriver {}
 
 /**
  * Mix a function from one object onto another. The function will still be
@@ -808,10 +735,10 @@ export class ProtractorBrowser extends AbstractExtendedWebDriver {
   /**
    * Waits for Angular to finish rendering before searching for elements.
    * @see webdriver.WebDriver.findElement
-   * @returns {!webdriver.promise.Promise} A promise that will be resolved to
+   * @returns {!webdriver.WebElementPromise} A promise that will be resolved to
    *      the located {@link webdriver.WebElement}.
    */
-  findElement(locator: Locator): WebElement {
+  findElement(locator: Locator): WebElementPromise {
     return this.element(locator).getWebElement();
   }
 
@@ -821,7 +748,7 @@ export class ProtractorBrowser extends AbstractExtendedWebDriver {
    * @returns {!webdriver.promise.Promise} A promise that will be resolved to an
    *     array of the located {@link webdriver.WebElement}s.
    */
-  findElements(locator: Locator): wdpromise.Promise<any> {
+  findElements(locator: Locator): wdpromise.Promise<WebElement[]> {
     return this.element.all(locator).getWebElements();
   }
 
diff --git a/lib/element.ts b/lib/element.ts
index 0d710701b..7b9319b50 100644
--- a/lib/element.ts
+++ b/lib/element.ts
@@ -2,7 +2,7 @@ import {By, error as wderror, ILocation, ISize, promise as wdpromise, WebDriver,
 
 import {ElementHelper, ProtractorBrowser} from './browser';
 import {IError} from './exitCodes';
-import {Locator} from './locators';
+import {isProtractorLocator, Locator} from './locators';
 import {Logger} from './logger';
 
 let clientSideScripts = require('./clientsidescripts');
@@ -159,7 +159,7 @@ export class ElementArrayFinder extends WebdriverWebElement {
         // This is the first time we are looking for an element
         return ptor.waitForAngular('Locator: ' + locator)
             .then((): wdpromise.Promise<WebElement[]> => {
-              if (locator.findElementsOverride) {
+              if (isProtractorLocator(locator)) {
                 return locator.findElementsOverride(ptor.driver, null, ptor.rootEl);
               } else {
                 return ptor.driver.findElements(locator);
@@ -170,7 +170,7 @@ export class ElementArrayFinder extends WebdriverWebElement {
           // For each parent web element, find their children and construct
           // a list of Promise<List<child_web_element>>
           let childrenPromiseList = parentWebElements.map((parentWebElement: WebElement) => {
-            return locator.findElementsOverride ?
+            return isProtractorLocator(locator) ?
                 locator.findElementsOverride(ptor.driver, parentWebElement, ptor.rootEl) :
                 parentWebElement.findElements(locator);
           });
@@ -905,7 +905,7 @@ export class ElementFinder extends WebdriverWebElement {
    * browser.driver.findElement(by.css('.parent'));
    * browser.findElement(by.css('.parent'));
    *
-   * @returns {webdriver.WebElement}
+   * @returns {webdriver.WebElementPromise}
    */
   getWebElement(): WebElementPromise {
     let id = this.elementArrayFinder_.getWebElements().then((parentWebElements: WebElement[]) => {
diff --git a/lib/locators.ts b/lib/locators.ts
index 5dbe7d7f3..b29132d82 100644
--- a/lib/locators.ts
+++ b/lib/locators.ts
@@ -1,9 +1,10 @@
-import {By, promise as wdpromise, WebDriver, WebElement} from 'selenium-webdriver';
+import {By, ByHash, promise as wdpromise, WebDriver, WebElement} from 'selenium-webdriver';
 
 let clientSideScripts = require('./clientsidescripts');
 
-
 // Explicitly define webdriver.By.
+// We do this because we want to inherit the static methods of webdriver.By, as opposed to
+// inheriting from the webdriver.By class itself, which is actually analogous to ProtractorLocator.
 export class WebdriverBy {
   className: (className: string) => By = By.className;
   css: (css: string) => By = By.css;
@@ -15,15 +16,21 @@ export class WebdriverBy {
   tagName: (tagName: string) => By = By.tagName;
   xpath: (xpath: string) => By = By.xpath;
 }
+export type WebDriverLocator = By | ByHash | Function;
 
 // Protractor locator strategy
-export interface Locator {
-  findElementsOverride?:
+export interface ProtractorLocator {
+  findElementsOverride:
       (driver: WebDriver, using: WebElement,
        rootSelector: string) => wdpromise.Promise<WebElement[]>;
   row?: (index: number) => Locator;
   column?: (index: string) => Locator;
 }
+export type Locator = ProtractorLocator | WebDriverLocator;
+
+export function isProtractorLocator(x: Locator): x is ProtractorLocator {
+  return x && (typeof(x as any).findElementsOverride === 'function');
+}
 
 /**
  * The Protractor Locators. These provide ways of finding elements in
@@ -70,7 +77,7 @@ export class ProtractorBy extends WebdriverBy {
    *     element. It should return an array of elements.
    */
   addLocator(name: string, script: Function|string) {
-    this[name] = (...args: any[]): Locator => {
+    this[name] = (...args: any[]): ProtractorLocator => {
       let locatorArguments = args;
       return {
         findElementsOverride: (driver: WebDriver, using: WebElement, rootSelector: string):
@@ -119,9 +126,9 @@ export class ProtractorBy extends WebdriverBy {
    * var deprecatedSyntax = element(by.binding('{{person.name}}'));
    *
    * @param {string} bindingDescriptor
-   * @returns {Locator} location strategy
+   * @returns {ProtractorLocator} location strategy
    */
-  binding(bindingDescriptor: string): Locator {
+  binding(bindingDescriptor: string): ProtractorLocator {
     return {
       findElementsOverride: (driver: WebDriver, using: WebElement, rootSelector: string):
                                 wdpromise.Promise<WebElement[]> => {
@@ -151,9 +158,9 @@ export class ProtractorBy extends WebdriverBy {
    * expect(element(by.exactBinding('phone')).isPresent()).toBe(false);
    *
    * @param {string} bindingDescriptor
-   * @returns {Locator} location strategy
+   * @returns {ProtractorLocator} location strategy
    */
-  exactBinding(bindingDescriptor: string): Locator {
+  exactBinding(bindingDescriptor: string): ProtractorLocator {
     return {
       findElementsOverride: (driver: WebDriver, using: WebElement, rootSelector: string):
                                 wdpromise.Promise<WebElement[]> => {
@@ -179,9 +186,9 @@ export class ProtractorBy extends WebdriverBy {
    * expect(input.getAttribute('value')).toBe('Foo123');
    *
    * @param {string} model ng-model expression.
-   * @returns {Locator} location strategy
+   * @returns {ProtractorLocator} location strategy
    */
-  model(model: string): Locator {
+  model(model: string): ProtractorLocator {
     return {
       findElementsOverride: (driver: WebDriver, using: WebElement, rootSelector: string):
                                 wdpromise.Promise<WebElement[]> => {
@@ -204,9 +211,9 @@ export class ProtractorBy extends WebdriverBy {
    * element(by.buttonText('Save'));
    *
    * @param {string} searchText
-   * @returns {Locator} location strategy
+   * @returns {ProtractorLocator} location strategy
    */
-  buttonText(searchText: string): Locator {
+  buttonText(searchText: string): ProtractorLocator {
     return {
       findElementsOverride: (driver: WebDriver, using: WebElement, rootSelector: string):
                                 wdpromise.Promise<WebElement[]> => {
@@ -229,9 +236,9 @@ export class ProtractorBy extends WebdriverBy {
    * element(by.partialButtonText('Save'));
    *
    * @param {string} searchText
-   * @returns {Locator} location strategy
+   * @returns {ProtractorLocator} location strategy
    */
-  partialButtonText(searchText: string): Locator {
+  partialButtonText(searchText: string): ProtractorLocator {
     return {
       findElementsOverride: (driver: WebDriver, using: WebElement, rootSelector: string):
                                 wdpromise.Promise<WebElement[]> => {
@@ -245,7 +252,7 @@ export class ProtractorBy extends WebdriverBy {
   };
 
   // Generate either by.repeater or by.exactRepeater
-  private byRepeaterInner(exact: boolean, repeatDescriptor: string): Locator {
+  private byRepeaterInner(exact: boolean, repeatDescriptor: string): ProtractorLocator {
     let name = 'by.' + (exact ? 'exactR' : 'r') + 'epeater';
     return {
       findElementsOverride: (driver: WebDriver, using: WebElement, rootSelector: string):
@@ -256,7 +263,7 @@ export class ProtractorBy extends WebdriverBy {
       toString: (): string => {
         return name + '("' + repeatDescriptor + '")';
       },
-      row: (index: number): Locator => {
+      row: (index: number): ProtractorLocator => {
         return {
           findElementsOverride: (driver: WebDriver, using: WebElement, rootSelector: string):
                                     wdpromise.Promise<WebElement[]> => {
@@ -267,7 +274,7 @@ export class ProtractorBy extends WebdriverBy {
           toString: (): string => {
             return name + '(' + repeatDescriptor + '").row("' + index + '")"';
           },
-          column: (binding: string): Locator => {
+          column: (binding: string): ProtractorLocator => {
             return {
               findElementsOverride: (driver: WebDriver, using: WebElement, rootSelector: string):
                                         wdpromise.Promise<WebElement[]> => {
@@ -283,7 +290,7 @@ export class ProtractorBy extends WebdriverBy {
           }
         };
       },
-      column: (binding: string): Locator => {
+      column: (binding: string): ProtractorLocator => {
         return {
           findElementsOverride: (driver: WebDriver, using: WebElement, rootSelector: string):
                                     wdpromise.Promise<WebElement[]> => {
@@ -294,7 +301,7 @@ export class ProtractorBy extends WebdriverBy {
           toString: (): string => {
             return name + '("' + repeatDescriptor + '").column("' + binding + '")';
           },
-          row: (index: number): Locator => {
+          row: (index: number): ProtractorLocator => {
             return {
               findElementsOverride: (driver: WebDriver, using: WebElement, rootSelector: string):
                                         wdpromise.Promise<WebElement[]> => {
@@ -365,9 +372,9 @@ export class ProtractorBy extends WebdriverBy {
    * var divs = element.all(by.repeater('book in library'));
    *
    * @param {string} repeatDescriptor
-   * @returns {Locator} location strategy
+   * @returns {ProtractorLocator} location strategy
    */
-  repeater(repeatDescriptor: string): Locator {
+  repeater(repeatDescriptor: string): ProtractorLocator {
     return this.byRepeaterInner(false, repeatDescriptor);
   }
 
@@ -387,9 +394,9 @@ export class ProtractorBy extends WebdriverBy {
    * expect(element(by.exactRepeater('car in cars')).isPresent()).toBe(true);
    *
    * @param {string} repeatDescriptor
-   * @returns {Locator} location strategy
+   * @returns {ProtractorLocator} location strategy
    */
-  exactRepeater(repeatDescriptor: string): Locator {
+  exactRepeater(repeatDescriptor: string): ProtractorLocator {
     return this.byRepeaterInner(true, repeatDescriptor);
   }
 
@@ -408,9 +415,9 @@ export class ProtractorBy extends WebdriverBy {
    *
    * @param {string} cssSelector css selector
    * @param {string} searchString text search
-   * @returns {Locator} location strategy
+   * @returns {ProtractorLocator} location strategy
    */
-  cssContainingText(cssSelector: string, searchText: string): Locator {
+  cssContainingText(cssSelector: string, searchText: string): ProtractorLocator {
     return {
       findElementsOverride: (driver: WebDriver, using: WebElement, rootSelector: string):
                                 wdpromise.Promise<WebElement[]> => {
@@ -441,9 +448,9 @@ export class ProtractorBy extends WebdriverBy {
    * expect(firstOption.getText()).toEqual('red');
    *
    * @param {string} optionsDescriptor ng-options expression.
-   * @returns {Locator} location strategy
+   * @returns {ProtractorLocator} location strategy
    */
-  options(optionsDescriptor: string): Locator {
+  options(optionsDescriptor: string): ProtractorLocator {
     return {
       findElementsOverride: (driver: WebDriver, using: WebElement, rootSelector: string):
                                 wdpromise.Promise<WebElement[]> => {