In spite of the fact that they've kept the references to the Incredible Hulk's standalone films to a minimum since the Avengers all started hanging out together in 2012, it appears Marvel considered bringing back The Abomination for Avengers: Age of Ultron.
During an interview with Crave Online, The Incredible Hulk's Tim Roth was asked whether there was any chance that he would come back as the character.
"They were going to do it," Roth said. "They did do that. They were thinking, in The Avengers 2 or something. There was a movie we could do that at one point, but way back when. It just kind of got swept under the carpet I guess. That would be hilarious."
Nobody from The Incredible Hulk has joined the cast of the larger Marvel Cinematic Universe since the movie was released, although characters like Major Glenn Talbot, who appears in Agents of S.H.I.E.L.D. and has connections to Hulk's General Thunderbolt Ross, have.