In the comics, Mitchell Carson is a high-ranking S.H.I.E.L.D. agent with a dark past, who’s chosen to become the third Ant-Man. He never gets that chance, however, as the suit is stolen and eventually lands in the hands of Eric O’Grady, who takes on the role instead. Carson then battles O’Grady and gets most of his face burned off, but eventually manages to capture and torture Ant-Man before being taken down by Iron Man.
Whether or not any of that will wind up in either Ant-Man or another upcoming Marvel film remain to be seen, but the secrecy surrounding the role suggests that Donovan’s part in the MCU is more than just fan service.
We’ll find out for sure when Ant-Man hits theaters later this month on July 17th, 2015.