Echo, originally known as CT-21-0408, is a clone trooper who served in the Grand Army of the Republic during the Clone Wars. He is a member of Clone Force 99, also known as the Bad Batch, a squad of elite clone troopers with genetic mutations. Echo's unique ability to interface with technology makes him an asset to the team, allowing him to hack into systems and gather intelligence. Throughout 'Star Wars: The Bad Batch,' Echo plays a crucial role in supporting his squad as they navigate the aftermath of the Clone Wars and the rise of the Galactic Empire.