Hexlock - Security app locker keeps apps private with smart profiles for any situation
KeepSafe - Keep your entire photo library safely stored in an encrypted private cloud.
AppLock (FOSS) - A privacy App lock FOSS application.
Super AppLock - * Protect installed apps using password or pattern! * Support PIN lock and Pattern lock!
Leo Privacy - Lock your Favorite apps like Whatsapp, Facebook, Wechat & Other Chat Messenger.
Hide Secrets - Hide Secrets is an app that allows hiding everything they deem confidential on their smartphone.