His name: Chopper.
Chopper is described as a lazy, cranky (but goodhearted) astromech droid.
“If Artoo is the family dog,” said Dave Filoni, executive producer of the show, “Chopper is the cat.”
The droid is a crew member of the Ghost and his job is to keep the starship running for the band of heroes.
Chopper’s design was inspired by Ralph McQuarrie’s early concept art for R2-D2, including the arms that fold out of his head. Star Wars Rebels takes place four years before Star Wars: Episode IV A New Hope, so Chopper’s “retro” look fits in with the droids in the original triology.
Star Wars Rebels is scheduled to premiere this fall as a one-hour special on Disney Channel, and will then air as a series on Disney XD channels around the world.