Lopez the Heavy

Lopez is a robot built by Sarge that only speaks Spanish due to a damaged voice card. After the Blue team captured him, he turned to their side due to a very strange series of events. He eventually falls in love with the Blue Team's tank, Sheila, thereby getting caught up in what Tucker refers to as the "twisted love triangle" between him, Caboose, and Sheila. When the cataclysmic explosion occurs, his body is destroyed, leaving him a head in alliance with O'Malley. How he gets around, operates a machine gun turret, or makes other robots for O'Malley is unknown; however, Simmons remarks that he's "very determined".

He disappeared from the series for several episodes, not appearing in Season 5 until Episode 96, where he is found in the cave in Blood Gulch, though it is not known how he got there.