"E.T." is a song by American singer Katy Perry from her third studio album, Teenage Dream (2010). She co-wrote the song with its producers Dr. Luke, Max Martin, and Ammo. "E.T." was serviced to radio stations as the album's fourth single on February 11, 2011. One version of the song features verses from American rapper Kanye West, and that version was included on the reissue of the album, Teenage Dream: The Complete Confection. Musically, it is an electronic and hip hop ballad which draws heavily from dubstep and techno, along with smaller amounts of drum and bass. According to Perry, the song lyrically speaks of "falling in love with a foreigner".

Katheryn Elizabeth Hudson, known professionally as Katy Perry, is an American singer, songwriter, and television personality. She is known for her influence on modern pop music and her camp style, being dubbed the "Queen of Camp" by Vogue and Rolling Stone. At 16, Perry released a gospel record titled Katy Hudson (2001) under Red Hill Records, which was commercially unsuccessful. She moved to Los Angeles at 17 to venture into secular music, and later adopted the stage name "Katy Perry" from her mother's maiden name. She recorded an album while signed to Columbia Records, but was dropped before signing to Capitol Records.