Yusuf Islam (born Steven Demetre Georgiou; 21 July 1948), commonly known by his stage names Cat Stevens, Yusuf, and Yusuf / Cat Stevens, is a British singer-songwriter and musician. He has sold more than 100 million records and has more than two billion streams. His musical style consists of folk, rock, pop, and, later in his career, Islamic music. Following two decades in which he performed only music which met strict religious standards, he returned to making secular music in 2006. He was inducted into the Rock and Roll Hall of Fame in 2014. He has received two honorary doctorates and awards for promoting peace as well as other humanitarian awards.

His 1967 debut album and its title song "Matthew and Son" both reached top 10 in the UK charts. Stevens' albums Tea for the Tillerman (1970) and Teaser and the Firecat (1971) were certified triple platinum in the US. His 1972 album Catch Bull at Four went to No. 1 on the US Billboard 200 and spent weeks at the top of several other major charts. He earned ASCAP songwriting awards in 2005 and 2006 for "The First Cut Is the Deepest", which has been a hit for four artists. His other hit songs include "Father and Son", "Wild World", "Moonshadow", "Peace Train", and "Morning Has Broken".

Stevens converted to Islam in December 1977, and adopted the name Yusuf Islam the following year. In 1979, he auctioned his guitars for charity, and left his musical career to devote himself to educational and philanthropic causes in the Muslim community. He has since bought back at least one of the guitars he sold as a result of the efforts of his son, Yoriyos. Stevens was embroiled in a controversy regarding comments he made in 1989, about the fatwa placed on author Salman Rushdie in response to the publication of Rushdie's novel The Satanic Verses. He has explained the incident stating: "I was cleverly framed by certain questions. I never supported the fatwa."

In 2006, he returned to pop music by releasing his first new studio album of new pop songs in 28 years, titled An Other Cup. With that release and subsequent ones, he dropped the surname "Islam" from the album cover art – using the stage name Yusuf as a mononym. In 2009, he released the album Roadsinger and, in 2014, he released the album Tell 'Em I'm Gone and began his first US tour since 1978. His second North American tour since his resurgence, featuring 12 shows in intimate venues, ran from 12 September to 7 October 2016. In 2017, he released the album The Laughing Apple, now using the stage name Yusuf / Cat Stevens, using the Cat Stevens name for the first time in 39 years. In September 2020, he released Tea for the Tillerman 2, a reimagining of his album Tea for the Tillerman to celebrate its 50th anniversary, and in June 2023, King of a Land, a new studio album.