Robert John Gaudio (born November 17, 1942) is an American songwriter, singer, musician, and record producer, and the keyboardist and backing vocalist of the pop/rock band the Four Seasons.

Gaudio wrote or co-wrote the vast majority of the band's music, including hits like "Sherry" and "December, 1963 (Oh, What a Night)", as well as "Can't Take My Eyes Off You" for Valli.

Though he no longer performs with the group, Gaudio and lead singer Frankie Valli remain co-owners of the Four Seasons brand.

While commercial success was elusive, the group was kept busy with session work (with Bob Crewe as the producer), and a string of performances at night clubs and lounges.

Crewe/Gaudio compositions also became major hits for other artists, including the Tremeloes ("Silence Is Golden", originally the B-side of the Four Seasons' "Rag Doll"), The Osmonds ("The Proud One", originally recorded as a Valli solo single) and the Walker Brothers ("The Sun Ain't Gonna Shine Anymore", another Valli single).

The appreciation of The Genuine Imitation Life Gazette has grown over the years, and it was re-released on CD (minus the newspaper cover) in the 1990s by Rhino in the U.S. and Ace in the UK.

Gaudio withdrew from touring in the early 1970s, a decision that fellow band member Joe Long indicated was due to stage fright and introversion.

The Bob and Judy songs became big hits for a reconstituted Four Seasons group (only Valli was left of the original lineup; Gaudio stopped touring with them in 1971 to concentrate on writing and producing).

Gaudio also produced the hit "You Don't Bring Me Flowers" for Barbra Streisand and Neil Diamond, a duet that reached the top of Billboard charts in 1978, for which he received a Grammy Award nomination.

Gaudio was instrumental in mounting Jersey Boys, a musical play based on the lives of the Four Seasons, which ran at the La Jolla Playhouse through January 2, 2005, and then opened on Broadway on November 6, 2005, to mostly positive reviews.

[11] On June 20, 2014, Warner Bros. released the film version of Jersey Boys, directed by Clint Eastwood, in which Gaudio was portrayed by Erich Bergen.

[13] On July 1, 2014, Rhino Entertainment released Audio with a G, the first compilation of the music composed by Bob Gaudio as performed by the Four Seasons, Frank Sinatra, Diana Ross, The Temptations, Cher, Roberta Flack, Nina Simone, Jerry Butler, Chuck Jackson and others.