Pain Bot is a robot created by Brother Blood to destroy the Titans, because "all he knows is pain". He was first used by Brother Blood to threaten Robin, Raven and Starfire into getting access to Titans Tower. They give him their voice codes willingly. Then, when Cyborg and Beast Boy arrive, they do not give him the codes because of their dedication to only saying waffles, and Pain Bot tortures them. When Brother Blood has finally had it with the word waffles, he and Pain Bot flee.
Later, in the episode Little Buddies, Brother Blood uses Pain Bot again to fight the Titans. Robin tells Beast Boy to "distract Blood by getting your face smashed in." Beast Boy gets the attention of Pain Bot to allow Robin a chance to throw Batarang at Blood's controller. The controller explodes, and Pain Bot is seemingly forgotten and left behind. He is taken to the Titans' Tower by Cyborg, and kept it as a "little buddy". Pain Bot seems to not be able to do anything without causing pain, but Cyborg seems to grow very fond of the robot. After the other Titans soon discover Pain Bot's presence in the house, they tell Cyborg that he must get rid of Pain Bot, which he reluctantly does, for a time. He soon sneaks the robot back and is confronted by Robin and the others. Citing that they all have "little buddies", some who may be deemed dangerous or evil, the Titans decide to have a fighting match between their "little buddies". Pain Bot eventually beats every little buddy, totaling seven rounds. His 8th opponent is Silkie, who eats Pain Bot in the first moment of the fight.
Pain Bot is a red metal robot with "Pain Bot" printed in yellow text on his front, along with three circular headlamps. He has a light bulb on top that flashes red whenever he speaks and has tank treads with three wheels providing motion.
- Standard arms and claws (capable of electrocution)
- Circular saw
- Knife blade
- Laser cannon
- Piranha attachment
- Metal Hammers
- "Pain! Pain! Pain!"
- "All I know is pain!"
- "Pain! Pain!"
- Pain Bot is voiced by Scott Menville, who is the voice actor for Robin. However in Brian, he is voiced by Khary Payton, the voice actor of Cyborg.
- Pain Bot is the first recurring villain in Teen Titans Go! to be created exclusively for the series.
- Pain Bot becomes Cyborg's friend in Little Buddies.
- He bears a noticeable resemblance to WALL-E, from the Disney Pixar film of the same name.
- Pain Bot seems to be able to inflict pain on people even without the remote. as shown when he tortures Robin in the living room of the tower.
- He is the only little buddy to be a robot.
- In the official closed captioning as seen on television, Pain Bot is commonly misquoted with "Oh, I know this hand" instead of the correct "All I know is pain".
- In More of the Same of the calendar, he is attacking the Titans instead being a little buddy.