John William Oates (born April 7, 1948) is an American musician, best known as half of the rock and soul duo Hall & Oates along with Daryl Hall. He has played rock, R&B, and soul music, serving as a guitarist, singer, songwriter, and record producer.

Although Oates's main role in the duo is being the guitarist, he also co-wrote many of the top 10 songs that they recorded, including: "Sara Smile" (referring to Hall's then-girlfriend, Sara Allen), "She's Gone", and "Out of Touch", as well as "You Make My Dreams", "I Can't Go for That (No Can Do)", "Maneater", and "Adult Education". He also sang lead vocals on several more singles in the Hot 100, such as "How Does It Feel to Be Back", "You've Lost That Lovin' Feelin'" (a remake of the 1965 song performed by the Righteous Brothers), and "Possession Obsession". In 1986, Oates contributed the song "(She's the) Shape of Things to Come" on the soundtrack to the 1986 film About Last Night. He also co-wrote and sang backup on the song "Electric Blue", recorded by the Australian band Icehouse, which was a Billboard top 10 hit.

Oates was inducted into the Songwriters Hall of Fame in 2004, and in 2014 was inducted into the Rock and Roll Hall of Fame, as a member of Hall & Oates. His memoir, Change of Seasons, was published in 2017.