A Deadhead or Dead head is a fan of the American rock band the Grateful Dead. The Deadhead subculture originated in the 1970s, when a number of fans began traveling to see the Grateful Dead in as many shows or festival venues as they could. As more people began attending live performances and festivals, a community developed. The Deadhead community has since gone on to create slang and idioms unique to them.

Due to extensive improvisation, eclectic song choice and other variables the Grateful Dead were known for having concerts perceived as each being a unique event. The wide variety of their live concerts, when coupled with the band's permissive attitude on taping performances, has created a plethora of historical material. Such recordings of previous performances are shared widely among the Deadhead community.

Much Deadhead-related historical material received or collected by the band over the years is housed in the Grateful Dead Archive of University of California, Santa Cruz. Archive founding curator Nicholas Meriwether, who has also written extensively about the culture and its impact on society, predicted, "The Grateful Dead archive is going to end up being a critical way for us to approach and understand the 1960s and the counterculture of the era... It's also going to tell us a lot about the growth and development of modern rock theater, and it's helping us understand fan culture." Over the course of their thirty-year career, the Grateful Dead performed over 2,200 live shows.

The eclectic musical styling of the Grateful Dead was heavily inspired by the Beatnik movement of the 1950s and later the psychedelic counterculture of the 1960s. One group at the forefront of the psychedelic sound was the Merry Pranksters. On the first historic bus trip, on the bus Furthur, a pattern was set for the Deadhead touring lifestyle to come. By the late 1970s, some Deadheads began to sell tie-dye T-shirts, veggie burritos, or other items at Grateful Dead concerts. In the 1980s, the area where Grateful Dead merchandise was sold became popularly referred to as "Shakedown Street", named after the 1978 song. Income from these shops allowed Deadheads a way to follow the band on its tours.

During the early 1980s, the number of Deadheads taping shows increased, and the band created a special section for fans who wished to record the show. These tapes are still shared and circulated today via websites such as the Live Music Archive and bt.etree.org. In the earlier days of the Grateful Dead, there were questions as to whether or not it was in the best interest of the band for fans to tape concerts. In 1982, Garcia himself was asked what he thought about it, and he replied, "When we are done with it [the concerts], they can have it."

The practice of taping has evolved and expanded in the digital age. The rise of the Internet and peer to peer file sharing networks has made it extremely easy for Deadheads to share concerts through unofficial and official channels. Bob Dylan, who toured with the Grateful Dead during their 1987 summer tour, observed "With most bands the audience participates like in a spectator sport. They just stand there and watch. They keep a distance. With the Dead, the audience is part of the band-they might as well be on stage."

The term "Deadhead" first appeared in print at the suggestion of Hank Harrison, author of The Dead Trilogy, on the sleeve of Grateful Dead (also known as Skull & Roses), the band's second live album, released in 1971. It read:

DEAD FREAKS UNITE: Who are you? Where are you? How are you?