Mercenary Brendan Doyle was hired by Edwin Cord, an industrialist whose company made the Mauler battlesuit but was imprisoned for his immoral business dealings (Cord also was responsible for the Raiders.) Doyle was hired to steal the Mauler suit from Stark International, where the battlesuit had been stored after Cord's business was bought by the company (IM #156). Doyle, however, discovered that his former Vietnam comrade-in-arms Jim Rhodes was working for Stark, and he owed Rhodey a debt -- his life! This debt ultimately led to Doyle being unable to fulfill his contract for the imprisoned Edwin Cord, thus he began a life of crime as a super-powered mercenary.
Tony Stark later realized that some of the circuits in the Mauler armor (among other armors) utilized principles stolen from the Iron Man armor. Stark, as Iron Man, began a crusade to neutralize the technology that had been stolen from him (in the classic "Armor Wars" saga, beginning in IM #225). When confronted by Iron Man, Doyle realized that he could not succeed in stopping Iron Man, and surrendered the Mauler suit without a fight.
First ever appearance: Daredevil #167.
First IM appearance: Iron Man #156.
