An American rock band which began as a side project for Grateful Dead rhythm guitarist Bob Weir and bassist Rob Wasserman in the late 1980s. The duo toured for 7 years under names such as Weir/Wasserman and Scaring the Children.

In 1994, Weir and Wasserman participated in the Woodstock '94 festival. Jay Lane was added on drums and Matthew Kelly on guitar and harmonica in 1995. They played their first show as a full band in April 1995, billed as Friends of Montezuma and then as Ratdog Revue. They played their first show as Ratdog in August 1995.

After the Grateful Dead disbanded in December 1995, following the death of Jerry Garcia, Ratdog became Weir's primary band. They mostly perform Grateful Dead material with a mixture of covers (including Bob Dylan and Chuck Berry), along with some originals. Ratdog's repertoire consists of over 150 songs.

The original line-up consisted of Weir on rhythm guitar, Wasserman on string bass, Kelly on lead guitar and Lane on drums. Grateful Dead keyboardist Vince Welnick joined the band in September 1995 and played in several shows but left a couple of months later. Dave Ellis became the band's first saxophonist in 1996 and remained until 1999 to be replaced by Kenny Brooks. Between 1996 and 1997, Johnnie Johnson and Mookie Siegel had stints as keyboardists. Jeff Chimenti became the keyboardist in May 1997 and is still in the band today. Kelly was replaced in 1998 briefly by Dave McNabb and then by current lead guitarist Mark Karan. Wasserman left the band in 2003 and was replaced by Robin Sylvester.

The current lineup consists of Weir, Lane, Chimenti, Karan, Brooks and Sylvester.

In June 2007, Karan was diagnosed with throat cancer. While he is undergoing treatment, Steve Kimock, the guitarist from the band Zero, who also has played with Dead spin-off bands the Other Ones and the Rhythm Devils in 2006, will take Karan's place for the time being.

Since its formation, many guest musicians have performed with Ratdog, including Grateful Dead members Mickey Hart, Bill Kreutzmann, Donna Jean Godchaux and Bruce Hornsby. Other well known guests include Joan Baez, Warren Haynes, Trey Anastasio, Les Claypool and Dickey Betts. The band has released 2 albums to date: Evening Moods (2000) and Live at Roiseland (2001).