He is a crudely drawn self-portrait of SpongeBob that comes to life.
Because he was created using a magic pencil (which belonged to a human artist at sea who accidentally threw it into Bikini Bottom, which SpongeBob and Patrick find), DoodleBob comes to life.
SpongeBob intended to use him to play a harmless prank on Squidward, only for DoodleBob to start beating him, swipe the magic pencil, and run away crazily, screaming gibberish. SpongeBob and Patrick chase him to where he had taken residence in a crudely drawn version of SpongeBob's pineapple house. When they corner him, SpongeBob erases DoodleBob with the magic pencil. However, unknown to SpongeBob and Patrick, SpongeBob misses one of DoodleBob's arms.
The arm infiltrates SpongeBob's house that night and then uses the magic pencil to restore himself (and also adds a pair of angry eyebrows) before attacking SpongeBob. During a chase, he erases a portion of Spongebob and his house.
As DoodleBob corners SpongeBob, he erases a portion of him (as possible payback) and plus mocks him, provoking SpongeBob. SpongeBob and DoodleBob then struggle with the pencil and cause it to break into halves. SpongeBob restores himself and DoodleBob sharpens his piece of the pencil (though SpongeBob accidentally flings his part of the pencil away through a window at Squidward's house).
DoodleBob corners SpongeBob once more, but when he is about to capture SpongeBob and literally erase him from existence, he gets stuck on a piece of paper. SpongeBob realizes this and then captures him in an empty book. The page he is trapped in soon sparkles and he develops a smile.
The next morning, Patrick comes to SpongeBob's house and asks what was making all the noise last night and sees DoodleBob framed on the wall. SpongeBob tells him what happened and says that DoodleBob was not evil but rather a "two-dimensional creature trapped in our three-dimensional aquatic world, longing for a purpose." Patrick says he still looks creepy.
He appears as one of SpongeBob's special abilities. However, he's actually a 3D model designed to look like a 2D drawing.
Drawn to Life: SpongeBob SquarePants Edition
Doodlebob is also the main antagonist of Drawn to Life: SpongeBob SquarePants Edition, in which he takes over Bikini Bottom using another magic pencil.
He speaks gibberish and in Drawn to Life: SpongeBob SquarePants Edition, when he is seen arguing with DoodlePants about something the text appears like random letters rather than "[DoodleBob speaking gibberish]" as seen in the closed-captions of "Frankendoodle."
At one point DoodleBob is heard speaking English when he says, "You doodle! Me SpongeBob!"