Facebook Design - Devices - Images and Sketch files of popular devices.
Craftwork - A collection of User Interface resources made by Craftwork
Design Cell - Beautiful multipurpose mockups for iOS
Icons8 - Free app for Mac & Windows already containing 39,800 icons. Allows to search and import icons…
Clay Mockups - Free set of beautiful device mockups for your designs
Previewed - Beautiful mockups & graphics for your next app