For mobile Movies & TV apps, jump to the Movies & TV section of the megathread.

MOBILE

► Mobile Apps

Movie Updates - Checks if the movies on your watchlist are uploaded online and sends you a notification as soon as they're available.
Lucky Patcher - Unlocks in-app purchases on Android apps and removes ads.
Newpipe - Watch and download youtube videos. Also offers ability to download from soundcloud.
YMusic - Youtube Music player and downloader
Tachiyomi - Manga reader
forum.mobilism.org - Forums with large catalogue of cracked apps and eBooks
Fildo - Music streaming app and downloader
apkmirror.com - Contains untouched and signed release apks. Useful if searching for a prior version of an application.

Streaming apps for Movies & TV listed under the Movies & TV section of the megathread
See /r/ApksApps for more android apps
See /r/sideloaded for iOS