Darrell is a robot created by Lord Boxman. Darrells play the role of Lord Boxman's loyal henchmen. They are built with brains which sit inside a compartment above the head, acting as the cranium. If Darrells are ever destroyed and come back, the next Darrell will remember what happened in its previous body. He first appeared in the series pilot as the main antagonist and is a recurring antagonist in OK K.O.! Let's Be Heroes, in which he was first briefly seen in Let's Be Heroes. He is also a boss in OK K.O.! Lakewood Plaza Turbo and an enemy in OK K.O.! Let's Play Heroes.
Darrell is a red robot with a slender and tall body. He only has one eye, instead of two eyes. His head is shaped like a square and holds a brain inside a light green compartment that is connected to the top of his head. He has a yellow circle on his chest that he can use to reset his robot form into a new one, along with two on the back of his hands, and also wears grayish black robotic boots. He has very sharp fingers and sharp teeth.
Darrells are known for their trickery, persistence, and childlike behavior. He hates the heroes of Lakewood Plaza Turbo, especially K.O., Rad, and Enid. Despite his temper and evil ways, he shows a soft side via a need for affection from his father, Lord Boxman. As a result, he is very receptive to any praise that Lord Boxman might give him. Darrell also has a never-ending rivalry with his sister figure Shannon.
Darrells can be described as being rather emotionally unstable, as they are easily aggravated. They can also become easily flustered by the pettiest of insults; this is one of Darrell's weaknesses.
Darrells can be customized in various ways (though not to the extent that Shannon's can), such having a laser cannon on one arm and a giant fist on the other. Darrells can also send out seemingly endless multiples of themselves.
Another notable customization is the Big Darrell robot, piloted by a normal sized Darrell within the head compartment, which has a power level of -100. This robot can only be beaten by a hero or force that equals up to power level 100 or higher. The Big Darrell was first seen in the episode You're Level 100!, when Lord Boxman created a robot to test KO's claim of him being level 100.
This form of Darrell has a cannon on his chest that can destroy the plaza in one blast. It is giant and also has giant and powerful artillery and weapons. It was destroyed by Turbo K.O. The Mega Darrell was first seen in the episode T.K.O.