Bullwhip (real name: Harold) was a teenager who is able to extract metal whips from his wrists and a supervillain in the animated TV series Batman Beyond. He is the main antagonist of episode "April Moon".
Bullwhip got these powers by enlisting the aid of Dr. Corso. He seemingly was not satisfied enough with the weapons. So, he and his gang kidnapped Dr. Corso's wife April and blackmailed him into making upgrades to his wrists.
However, Batman got involved and the gang overpowered him the first time.
After stalking them to their hideout, Batman and Dr. Corso found out that April wasn't kidnapped, but there willingly and was having an affair with Bullwhip. Dr. Corso panicked and fled.
After Batman disabled all his teammates, Bullwhip returned to Dr. Corso asking him to upgrade his wrists again and "don't hold back", unaware that Corso knew everything. Dr. Corso took his drill out and Bullwhip's words literally and proceeded to work on his wrists.
Bullwhip's ultimate fate is unknown but Bruce implied that Dr. Corso most likely murdered him or at least maimed or lobotomized him.
- All the members of the "April Moon Gang" are inspired by Marvel Comics characters. In the case of Bullwhip, it is Omega Red.