Steven Maxwell "Steve" Porcaro (born 2 September 1957, Hartford, Connecticut) is a keyboardist and composer who was an original member of the rock / pop band, Toto.Porcaro wrote the song "Takin' It Back" for Toto's first album, and the song was released as a single together with the hit, "Hold The Line".

He also wrote "It's A Feeling" for Toto IV and "Lea" for Fahrenheit. He left Toto in 1986 after the Fahrenheit record in order to pursue a more full-time songwriting and composing career. Another significant credit to note is that Porcaro composed the music for the song "Human Nature" from Michael Jackson's album Thriller.

However, Porcaro has continued working with Toto in various supporting capacities, assisting with keyboards, drum looping, synthesizers and arranging/composing. He has also done session musician work for many other acts, including Yes and Jefferson Airplane.

His brother, Mike Porcaro, is Toto's bass player. In addition Steve's late brother, Jeff Porcaro, was Toto's co-founder and drummer from 1977 until his death on August 5, 1992."Rosanna", Toto's popular 1982 Grammy winning single, was written for him by the band's primary songwriter, David Paich.

The song was in reference to Steve's relationship at the time with the actress, Rosanna Arquette.Porcaro is currently working on film scores and is credited as an additional keyboardist on Toto's current release, Falling in Between (released in February 2006).

He is planning to tour with Toto on their 30th year anniversary in 2007, together with fellow ex-member Joseph Williams.