Google Photos - All your photos are backed up safely, organized and labeled automatically, so you can find them fast, and share them how you like.
F-Stop Media Gallery - Image and video organizer.
Photok - A safe place for your photos. It stores your photos encrypted on your device and hides them from others.
Piktures - The first gesture-based gallery app to manage your albums of photos and videos.
Privary - Software to hide private photos and videos.
Camera Roll - Simple Gallery App for Android, with lovely Material Design.