3. Telepathy
Marvel ComicsPotentially, the power of Thanos' that the heroes of the Marvel Cinematic Universe will be most helpless against is his outrageous level of telepathy. Thanos can read minds, speak to other characters telepathically and essentially destroy his opponent's minds with a telepathic assault. In the comic books, he has displayed the impressive ability to successfully defend himself from a psychic assault by Moondragon - a character whose psionic powers are up there with people like Professor Charles Xavier. He has also used his abilities to mentally trigger great rage in the Hulk - a tactic he could potentially employ against the Avengers in the Marvel Cinematic Universe - and, with some augmentation, he has been able to communicate with Galactus telepathically (Galactus being the abstract cosmic entity who eats planets and who Professor X can't even touch telepathically). As things stand, the Marvel Cinematic Universe's characters are all telepathically vulnerable and none of them possess telepathy themselves (Loki has displayed something resembling telepathy, but not even close to the scale of Thanos and it was probably more magic-related in his case anyway), so Tony Stark might need to put his inventing cap on and build an armour with some telepathic protection in it - otherwise Thanos could turn him and his heroic friends in to his play-things.