Bob Flanagan (26 December 1952, New York City – 4 January 1996, Long Beach, California) was an American performance artist, poet, writer, comedian, and musician known for his exploration of BDSM and themes of pain in his work. Diagnosed with cystic fibrosis, a rare and incurable genetic disorder, Flanagan faced chronic physical suffering throughout his life. He was married to Sheree Rose (b. 1941) from 1989 until his death in 1996; Rose, who served as Flanagan's muse, producer, and primary collaborator, donated his archives to USC's ONE National Gay & Lesbian Archives in 2014.

Flanagan grew up in Costa Mesa, California, with two brothers and a sister, who succumbed to cystic fibrosis at the age of 21. He was diagnosed with the disease early in his childhood and endured mucus build-up and recurrent respiratory infections throughout his life. He pursued literature studies at California State University, Long Beach, and the University of California, Irvine, ultimately settling in Los Angeles in 1976. It was there that he became involved with the poetry community at Beyond Baroque Literary Arts Center, engaging in public readings across Southern California. His first book, The Kid is the Man, was published in 1978.

In 1980, Flanagan met Sheree Rose, marking the beginning of their significant collaboration and "Master-Slave" relationship. Together, they established an LA chapter of the Society of Janus, the second official BDSM organization in the United States. Their inaugural performance, Nailed, took place in 1989, where Flanagan famously hammered down his penis and scrotum to a woodblock while singing "If I Had a Hammer," a well-known pop schlager by Pete Seeger and Lee Hays. This performance coincided with the release of Modern Primitives, a book by Andrea Juno and V. Vale that examined body modification, published by RE/Search Publications.

Flanagan's most recognized exhibition, Visiting Hours, premiered in 1992 at the Santa Monica Museum of Art and was later showcased at New York City's New Museum in 1994. This installation featured Flanagan's writings and videos, presenting him in his hospital bed interacting with visitors.

In 1992, Flanagan gained notoriety for his appearance in the controversial music video for "Happiness in Slavery" by Nine Inch Nails, which faced censorship in multiple countries due to its graphic content. The video depicted Flanagan undergoing brutal torture with mechanical devices, filmed without special effects. He also appeared in Danzig's 1993 video "It's Coming Down," where he pierced his lips together and hammered a nail through the head of his penis, with the footage capturing blood directly on the camera lens. A "totally uncensored" version of this video was featured in a DVD/VHS compilation released in 2003. Additionally, Flanagan made a brief cameo in Godflesh's 1994 video "Christbait Rising," suspended upside-down from a church ceiling.

Flanagan passed away in January 1996 at the age of 43 due to complications from cystic fibrosis. During his later years, he was accompanied by filmmaker Kirby Dick, who documented their public engagements and intimate conversations with Sheree Rose. Flanagan agreed to collaborate with Dick on the condition that the resulting film would include his death. The documentary, titled Sick: The Life and Death of Bob Flanagan, Supermasochist, premiered at the Sundance Film Festival in January 1997, where it received a "Special Jury Recognition" award.