Foreigner is a British-American rock band formed in New York City in 1976 by guitarist Mick Jones, vocalist Lou Gramm, drummer Dennis Elliott, keyboardist Al Greenwood, bassist Ed Gagliardi and multi-instrumentalist Ian McDonald, the last of whom was also a founding member of King Crimson. Foreigner is one of the world's best-selling bands of all time, with worldwide sales of more than 80 million records, including 37.5 million in the US.

Jones came up with the band's name as he, Elliott and McDonald were British, while Gramm, Greenwood and Gagliardi were American, meaning at least half of the band would be foreigners no matter what country they were in. In 1977, Foreigner released its self-titled debut album, the first of six consecutive albums (including the 7x platinum 1982 greatest hits album Records) to be certified multi-platinum and go Top 10 in the US. The album produced two US Top 10 singles in "Feels Like the First Time" and "Cold as Ice". Their 1978 follow-up, Double Vision, was even more successful, and included two more US hits in "Hot Blooded" and the title track. Rick Wills replaced Gagliardi on bass before Foreigner recorded their third album, Head Games (1979), which included the US Top 20 singles "Dirty White Boy" and the title track. After the departures of McDonald and Greenwood reduced the band to a quartet, their next album 4 (1981) hit No. 1 for 10 weeks in the US, and became Foreigner's break-through album in the UK, going Top 5 there. The album produced three hit singles: "Urgent", "Waiting for a Girl Like You" and "Juke Box Hero". In 1984, Foreigner issued their fifth studio album Agent Provocateur, which reached No. 1 in the UK and included their biggest hit single "I Want to Know What Love Is", a No. 1 hit in the US, UK, Canada, and Australia, No. 3 in Germany and Top 10 in numerous other countries. A second hit from the album, "That Was Yesterday", went Top 20 in the US.

After a break, Foreigner released Inside Information (1987). Despite two more US Top 10 hits in "Say You Will" and "I Don't Want to Live Without You", it became their first album not to go multi-platinum or Top 10 in the US, achieving single platinum sales and peaking at No. 15. Since 1990, the band has undergone several more line-up changes, including the departures of Elliot and Wills in 1991, while Gramm left the band in 1990, returned in 1992 and left again in 2003. The three studio albums the band have released during these years - Unusual Heat (1991), Mr. Moonlight (1994), and Can't Slow Down (2009) - were not major sellers, although the 1992 greatest hits album The Very Best ... and Beyond, which included three new songs, did go 2x platinum in the US and gold in the UK.

Since 2003, Mick Jones has been the only founding member still involved with Foreigner, though there have been several instances of the band touring without him in recent years. Two of the founding members, Ed Gagliardi and Ian McDonald, died in 2014 and 2022 respectively. Since 2013, there have been occasional quasi-reunion tours, concerts, and other guest appearances from varying combinations of former band members Gramm, Elliot, Wills, Greenwood, and (before his death) McDonald. In 2024, Foreigner was selected as a Rock and Roll Hall of Fame inductee.