Mad Dog is a name used by several characters from the DC Universe, but the most known is Martin Hawkins, the first Arkham Asylum patient.
Hawkins was a serial killer who raped and murdered several women. In 1921, he escaped a facility in Metropolis and killed Constance and Harriet Arkham, the wife and daughter of Amadeus Arkham. Amadeus later killed him using electroshock therapy.
In the Prime Earth, Mad Dog was a bounty hunter named Rex who worked for the League of Assassins. He was sent after the Suicide Squad, but he eventually drafted into the team. His appearance seems to be based on Lawrence Crock aka Sportsmaster from the animated series Young Justice.
Martin Hawkins was created by Grant Morrison and Dave McKean, first appearing in Arkham Asylum: A Serious House on Serious Earth (1989). Mad Dog from The New 52 was created by Adam Glass, first appearing in Suicide Squad (Volume 4) #3 (2012).
Prime Earth
Arkham City: The Order of the World
Prime Earth
Suicide Squad villain
Multiverse
Other Media
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