Cynthia Slater (1945–1989) was an American BDSM activist best known for being in 1974 one of two founders (the other being Larry Olsen) of the Society of Janus, the second BDSM organization founded in the United States (after The Eulenspiegel Society).
She was friends with Guy Baldwin, who was the first openly gay man to be part of the Society of Janus. Soon after Baldwin’s arrival in San Francisco, he spotted a tiny classified ad in the back pages of The Berkeley Barb, the infamous underground newspaper, and decided to attend the advertised meeting for “fans of S and M and B and D.” As it turned out, Slater was hosting a monthly “rap meeting” in her living room which was (at the time) the meeting of the Society of Janus. Baldwin and Slater became fast friends, and he was soon teaching classes for the Society of Janus.
Slater was an early proponent of S/M safety. She hosted Society of Janus safety demonstrations during the late 1970s. In 1981 she and David Lourea presented safer-sex education workshops in BDSM clubs in San Francisco. According to first-hand accounts, she coined the term “SM 101”, referring to the safety demonstrations and classes she presented.
She also contributed to developing and disseminating kink-friendly safer sex technologies.
Slater was also known for persuading the management of San Francisco’s S/M leather club the Catacombs, the most famous fisting club in the world, to open up to lesbians; it was originally a gay men’s club.
She also worked as a professional dominatrix, and was photographed as such by noted BDSM photographer Robert Mapplethorpe.
She was the first woman profiled in the magazine Drummer.
She died of AIDS in 1989, and is among those commemorated in the AIDS Quilt.
Slater was openly bisexual. She had three children.
In 2003, she received the Forebear Award as part of the Pantheon of Leather Awards.
In 2014, Slater was inducted into the Leather Hall of Fame.
In 2017, the art installation known as the San Francisco South of Market Leather History Alley was installed; in it Slater (among others) is honored with a bronze bootprint displaying her name and a short statement about her.
She is an inductee of the Society of Janus Hall of Fame.