Marc Stevens (born February 9, 1943 – August 1989) was an American erotic performer. He is sometimes credited as Mark '10 1/2' Stevens or Mark Stevens.

Stevens was a pioneering sex industry figure during the 1970s in New York City. He appeared in over 80 pornographic movies, and also led an erotic dance troupe and performed in live sex shows. While he predominantly appeared in heterosexual films and loops, he was bisexual and made a number of gay movies as well. He was a close associate of leading sex industry figures such as Jason & Tina Russell, Annie Sprinkle, who was also his neighbour for a time, Sharon Mitchell, Jamie Gillis, Georgina Spelvin and Gloria Leonard.

He had the nickname "10 1/2" because of the supposed size of his penis. That same penis was famously photographed by Robert Mapplethorpe.

Typical of 1970s porn figures, he developed a serious drug problem. In his later years, he dropped out of the porno industry and became a drug pusher and, according to Sharon Mitchell, a pimp; Stevens died of AIDS in 1989, aged 46.

Despite his prominence in the 1970s, and the fact he produced two memoirs (long out of print and allegedly ghost-written by his mother) one of which was named "10 1/2!". Stevens has attracted relatively little attention since. This may change due to the continuing and growing interest in the films made in this period, i.e. the so-called "Golden Age of Porn".

Notable films featuring Marc Stevens include: The Devil in Miss Jones, All about Gloria Leonard, and Michael, Angelo and David, a gay classic.

Date of Death: 1989
Years Active as a Director: 1977
In 1989 Marck Stevens became one of the growing ranks of adult stars that have succumbed to AIDS.