Synthetic ponies who are programmed to believe they are actually alive. They will always act appropriately to a situation, but only as part of their programming. Robots are considered very dangerous, and are expected to go on a rampage if they ever learn the truth about themselves.

Dr. Dragonshy created all of the Robots.

Robots are controlled by the mice that live in Equestria.

The others know that Sweetie Bot is a Robots, but haven't done anything to avoid the inevitable rampage.