Official Characters Pack (OCP) for Marvel Ultimate Alliance (MUA) was created to add the DLC content of the Xbox 360 verison to the original PC version ported by Beenox in 2006.
Maybe an optional file that lets you bring along one of the Skrull bosses with you in the Aeronautics even if a member(s) of the F4 is on your team? (You aren't able to normally, as the F4 doesn't trust them)
Request by Cyborg Sun