2. Iron Man/Thor/Captain America (The Avengers)
Marvel StudiosThe appetite for grudge matches in comic books is neatly encapsulated by the fact that long-time rivals Marvel and DC successfully engineered a crossover purely to pit their biggest superhero teams against each other (its called JLA/Avengers, if youre interested). Crossovers are beyond the cinematic universe at this stage and seem highly unlikely in the future, but the MCU offered the next best thing when Thor clashed with Iron Man early on in The Avengers. Tony Stark picks a fight with Thor, whos attempting to talk some sense into Loki, by tackling him mid-conversation, in a typically subtle move. What follows is a masterpiece of comic book logic: Thors lightning supercharges the Iron Man suit, Tonys sent flying by a headbutt, and Mjolnir and Caps shield meet in an explosion of sparks. Its pure popcorn fodder, and lets not forget Tonys immortal snipe at Thors unconventional dress sense: Doth Mother know you weareth her drapes?