John Joseph Lydon (; born 31 January 1956), also known by his former stage name Johnny Rotten, is a singer, songwriter, author, and television personality. He was the lead vocalist of the punk rock band the Sex Pistols, which was active from 1975 to 1978, and again for various revivals during the 1990s and 2000s. He is also the lead vocalist of post-punk band Public Image Ltd (PiL), which he founded and fronted from 1978 until 1993, and again since 2009.

Lydon's outspoken personality, rebellious image and fashion style convinced Sex Pistols manager Malcolm McLaren to invite Lydon to join the group as its lead vocalist. With the Sex Pistols, he penned singles including "Anarchy in the U.K.", "God Save the Queen", and "Holidays in the Sun", the content of which precipitated what one commentator described as the "last and greatest outbreak of pop-based moral pandemonium" in Britain. The band scandalised much of the media, and Lydon was seen as a figurehead of the burgeoning punk movement. Due to their controversial lyrics and disrepute at the time, they are regarded as one of the most influential acts in the history of popular music.

After the Sex Pistols disbanded in 1978, Lydon founded his own band, Public Image Ltd, which was far more experimental in nature and described in a 2005 review by NME as "arguably the first post-rock group". The band produced eight studio albums and a string of singles, including "Public Image", "Death Disco", and "Rise", before they went on hiatus in 1993, reforming in 2009. In subsequent years, Lydon has hosted television series in the UK, US, and Belgium, in 2004 appeared on I'm a Celebrity ... Get Me Out of Here! in the UK, appeared in advertisements on UK television promoting Country Life, a brand of British butter, written two autobiographies, and produced solo musical work, such as the studio album Psycho's Path (1997). In 2005, he released a compilation album, The Best of British £1 Notes.

In 2015, there was a revival of a 1980s movement to have Lydon knighted for his achievements with the Sex Pistols, although he declined an MBE for services to music. Q magazine remarked that "somehow he's assumed the status of national treasure".