Óscar Luis Castañeda Lossio (born 21 June 1945) is a Peruvian politician who was Mayor of Lima, the capital city of Peru, from 2003 to 2010.
He became Mayor of Lima again in 2015, after being elected for a third nonconsecutive term with 51% of the popular vote, for a term that lasted until December 2018.
He ran for President of Peru in 2000, prior to his mayoral campaign, and in 2011, coming in fifth place with 9% of the vote.