A free app for Android, by Wasabi.

Halloween Live Wallpaper is the best Halloween night live wallpaper with a scary background and flying bats! You can set the background as your home screen or lock screen and you can choose from 4 different Halloween backgrounds: pumpkin, ghost, flying bats, and witch. All of them are really scary and they will make your phone or tablet look really spooky! You can choose the color of the Halloween background and you can also set the speed of the moving bats to slow or normal.

The app has been tested to work on the latest Android devices, so if you’re using an old phone, it might not work.