Joaquin Rafael Phoenix (/hwɑːˈkiːn ˈfiːnɪks/; né Bottom; born October 28, 1974), known formerly as Leaf Phoenix, is an American actor, music video director, producer, musician, and social activist. He started his career as a child actor and later came to wide attention for his portrayal of Commodus in the 2000 historical epic film Gladiator which earned him a nomination for the Academy Award for Best Supporting Actor as well as nominations for the Golden Globe Award, Screen Actors Guild, Satellite Award, and BAFTA Award.

He received wider recognition for his portrayal of musician Johnny Cash in the 2005 biographical film Walk the Line. His performance earned him several accolades and nominations, including the Golden Globe Award for Best Actor – Motion Picture Musical or Comedy and nominations for the Academy Award for Best Actor, Screen Actors Guild and BAFTA Award. He received his third Academy Award nomination for his critically acclaimed performance in the 2012 film The Master as well as his third nomination for a Golden Globe Award and BAFTA Award. In 2013, he received his fourth nomination for the Golden Globe Award in the category Best Actor – Motion Picture Musical or Comedy, for his role as Theodore Twombly in Spike Jonze's film Her.