Easily identified by their distinctively grotesque costumes, Gwar's core thematic and visual concept revolves around an elaborate science fiction-themed mythology which portrays the band members as barbaric interplanetary warriors, a narrative which serves as the basis for all of the band's albums, videos, live shows and other media. Rife with over-the-top violent, sexual, and scatological humor typically incorporating social and political satire, Gwar has attracted both acclaim and controversy for its music and stage shows, the latter of which notoriously showcase enactments of graphic violence that result in the audience being sprayed with copious amounts of fake blood, urine, and semen. Such stagecraft regularly leads Gwar to be labeled a "shock rock" band by the media.
The band's characteristic costumes are generally made of foam latex, polystyrene foam, and hardened rubber. The costumes cover very little of the band members' bodies; the bare parts are accentuated with makeup. They further their production in concert by spraying their audiences with fluids. Most of the fluids are made of water and powdered food coloring which, for the most part, flakes off or washes out easily. The thicker fluids are made from a clear seaweed extract called carrageenan, which is also used in ice cream and milkshakes. Gwar does not use syrups or stage blood because they dry solid and can damage the band's costumes.