Dr. Luke, Ammo and Max Martin, the three producers behind E.T., originally intended the song for Oscar-winning hip-hop group Three 6 Mafia. It was only by mistake that Katy Perry heard the basic beat while in the studio with them, and immediately recognized its potential in fitting well with the themes she had in mind: “I heard it and I always knew I wanted to write this futuristic, ‘alienistic’ song, and they pulled it up and I was like, ’Wait, I can wrap my head around this. I know this seems like a long shot, but I think I have the perfect material to put on top of this sound.’”
And it definitely worked, even though after the completion of the song Perry was unsure of its potential as a single. The task of following California Gurls, Teenage Dream and Firework, all previous number ones from the same album, was not an easy one. So in order to make sure she picked the right song as the follow-up, the pop singer asked her fans via Twitter about which Teenage Dream track they feel should be released as a single.
E.T. features guest rapping by Kanye West, whose contributions received mixed opinions. Digital Spy felt they were “entirely needless” while Vulture were more critical of his inappropriate sexual metaphors: “Tell me what’s next, alien sex / Imma disrobe you, then Imma probe you / see I abducted you / so I tell you what to do.” On the other hand, Entertainment Weekly felt the song benefited from a male’s perspective, and National Post called it simply a “great duet”.