Grateful Dead was an American rock band formed in 1965 in Palo Alto, California. The band is known for its eclectic style, which fused elements of rock, blues, jazz, folk, country, bluegrass, rock and roll, gospel, reggae, and world music with psychedelia, the improvisation of their live performances, and its devoted fan base, known as "Deadheads". According to the musician and writer Lenny Kaye, the band's music "touches on ground that most other groups don't even know exists." For the range of their influences and the structure of their live performances, Grateful Dead are considered "the pioneering godfathers of the jam band world".

Grateful Dead was founded in the San Francisco Bay Area during the rise of the counterculture of the 1960s. The band's founding members were Jerry Garcia (lead guitar and vocals), Bob Weir (rhythm guitar and vocals), Ron "Pigpen" McKernan (keyboards, harmonica, and vocals), Phil Lesh (bass guitar and vocals), and Bill Kreutzmann (drums). Members of Grateful Dead, originally known as the Warlocks, had played together in various Bay Area ensembles, including the traditional jug band Mother McCree's Uptown Jug Champions. Lesh was the last member to join the Warlocks before they changed their name to Grateful Dead, replacing Dana Morgan Jr., who had played bass for a few gigs. Drummer Mickey Hart and non-performing lyricist Robert Hunter joined in 1967. With the exception of McKernan, who died in 1973, and Hart, who took time off from 1971 to 1974, the core of the band stayed together for its entire 30-year history. Other official members of the band included Tom Constanten (keyboards from 1968 to 1970), John Perry Barlow (non-performing lyricist from 1971 to 1995), Keith Godchaux (keyboards and occasional vocals from 1971 to 1979), Donna Godchaux (vocals from 1972 to 1979), Brent Mydland (keyboards and vocals from 1979 to 1990), and Vince Welnick (keyboards and vocals from 1990 to 1995). Bruce Hornsby (accordion, piano, vocals) was a touring member from 1990 to 1992, as well as a guest with the band on occasion before and after the tours.

After Garcia's death in 1995, former members of the band, along with other musicians, toured as The Other Ones in 1998, 2000, and 2002, and as The Dead in 2003, 2004, and 2009. In 2015, the four surviving core members marked the band's 50th anniversary in a series of concerts that were billed as their last performances together. There have also been several spin-offs featuring one or more core members, such as Dead & Company, Furthur, the Rhythm Devils, Phil Lesh and Friends, RatDog, and Billy & the Kids.

Despite having only one top-40 single in their 30-year career, "Touch of Grey", Grateful Dead remained among the highest-grossing American touring acts for decades. They gained a committed fanbase by word of mouth and through the free exchange of their live recordings, encouraged by the band's allowance of taping. In 2024, they broke the record for most top-40 albums on the Billboard 200 chart. Rolling Stone named Grateful Dead number 57 on its 2011 list of the "100 Greatest Artists of all Time". The band was inducted into the Rock and Roll Hall of Fame in 1994 and a recording of their May 8, 1977 performance at Cornell University's Barton Hall was added to the National Recording Registry of the Library of Congress in 2012.