Motörhead () were an English rock band formed in London in 1975 by bassist and lead vocalist Lemmy Kilmister, guitarist Larry Wallis and drummer Lucas Fox. Lemmy was also the primary songwriter and only constant member. The band are often considered a precursor to the new wave of British heavy metal, which re-energised heavy metal in the late 1970s and early 1980s. Though several guitarists and drummers have played in Motörhead, most of their best-selling albums and singles feature drummer Phil "Philthy Animal" Taylor and guitarist "Fast" Eddie Clarke. From 1995 until the band's break-up in 2015, the group consisted of Lemmy, Mikkey Dee (drums) and Phil Campbell (guitar).

Motörhead released 23 studio albums, 10 live recordings, 12 compilation albums and five EPs over a career spanning 40 years. Usually a power trio, they had particular success in the early 1980s with several successful singles in the UK Top 40 chart. The albums Overkill, Bomber, Ace of Spades and, particularly, the live album No Sleep 'til Hammersmith cemented Motörhead's reputation as a top-tier rock band. The band are ranked number 26 on VH1's 100 Greatest Artists of Hard Rock. By 2023, the band has sold more than 30 million albums worldwide.

Most often classified as heavy metal, Motörhead has been credited with being part of and influencing numerous musical scenes, thrash metal and speed metal especially. Lemmy, however, always insisted that they were a rock and roll band. He said they had more in common with punk bands, but with their own unique sound, Motörhead is embraced in both punk and metal scenes. Their lyrics typically covered such topics as war, good and evil, abuse of power, promiscuity, substance abuse and, most famously, gambling, the last theme being the focus of their hit song "Ace of Spades".

Lemmy died on 28 December 2015 from cardiac arrhythmia and congestive heart failure, after being diagnosed with prostate cancer. The day after his death, longtime members Dee and Campbell both confirmed that Motörhead had disbanded. By 2018, all three members of Motörhead's best-known line-up (Lemmy, Taylor and Clarke) had died.