Culebra

 is a minor antagonist in the series.

Bio
A snake-like monster who can breathe heat. In "The Rat," Culebra gains the ability to raise Earth's heat. When the Galactic Sentinels attack Culebra when the sun sets, Emperor Gorganus recalls Culebra. Emperor Gorganus modifies Culebra with a power retainer and sends him back to Earth. Due to Gordon ending up in the body of Swinton's rat, the others had to fight Culebra without him while Nimbar found a way to undo what happened to Gordon. Once Nimbar found a way to get Gordon back to normal, Gordon joined up with the other Galactic Sentinels to help fight Culebra. The Galactic Sentinels weren't able to form Knighttron until Gordon teleported by to Knighttron and got Darwin off the teleporter pad. Once this was done and Knighttron was formed, Culebra was defeated and withdrawn by Emperor Gorganus. In "Emperor for a Day," Gorganus puts Lechner in charge and he sends Culebra to attack and pulls him back and sends him back later. This almost defeats the Sentinels until Gorganus returns. He can make fireballs from his mouth.

Appearance
Culebra has a body much like that of a king cobra. However, he has two arms and two legs, giving him a lizard-like appearance.