In the end of Thor Ragnarok, Thor looks through the rubble of Asgard to make sure the 2nd infinity gauntlet is secure. He sees a figure stand there... tall, glowing eyes very ominous and a glowing green object pertruding his head. Thor yells "WHO ARE YOU?!" And throws his hammer. The man to thors surprise catches it and yields it in his hand with the 2nd infinity gauntlet on. The man then replies "Humanities last hope.".
The mysterious man is Adam Warlock in possession of the 2nd infinity gauntlet.