Born in Madison, Fla. In 1927, Messer was the only child of Henry and Sarah Messer. His father owned a Chevrolet dealership, his mother was a homemaker.
He moved to Durham, N.C. to study premed at Duke University and went on to the Duke University School of Medicine. During the Korean conflict, Messer entered the Air Force as a first lieutenant and began his specialization in neurosurgery under orders from his commanding officer at Maxwell Air Force Base in Montgomery, Ala., where he was stationed throughout the war.
It was there that he met his partner of 62 years, Carl House. The two met after a night out with a group of gay servicemen. But shortly thereafter, an officer with whom Messer had been involved turned him in for being gay. Messer resigned his commission after a three-month investigation.
In 1953, Messer and House moved to New York, where Messer completed his residency in neurosurgery at St. Vincent's Hospital. The couple bought a home in Greenwich Village and also several rental properties. They would live there for 14 years.
In 1974 Messer authored a chapter entitled "The Homosexual as Physician" for Human Sexuality: A Health Practitioner's Text, the first account of gay doctors to be included in a medical textbook.
Two years later he listed the chapter on his curriculum vitae when he applied to join the staff of Wayne County General Hospital in Westland, Mich., then a teaching site for the University of Michigan Medical School, so he was hired as an out gay man, perhaps one of the first in his profession.
In January 1985, an undercover police officer arrested Messer at the Irving Art Theater for alleged indecent behavior. He was convicted, fined, and placed on one year's probation.As a result of his conviction, New York State revoked his medical license. Although his Michigan license was never in jeopardy, Messer decided to retire at age 60.
In 1991, at age 63, he co-founded the Triangle Foundation. A member of Triangle's board of directors for many years, Messer was also an active volunteer for the group. He performed data entry at Triangle's office in Northwest Detroit and often made lunch for the office staff. He received the Lifetime Achievement Award at the annual Pride banquet on June 15th, 1995. Thirteen days later, on June 28th, he was shot and wounded while working in the Triangle office. The act of anti-gay violence received national attention.
Triangle Foundation merged with Michigan Equality in 2010 and became Equality Michigan. On October 21 2014, Michigan Equality said in a press release it had received $3 million from the estate of Henry Messer. More than $1 million will go directly to the organization, while the additional money was donated to the Community Foundation for Southeast Michigan that contains Equality Michigan’s endowment.