During his career he sought to achieve a form of "total theater" described by The New York Times as "wittily physical", and which earned him a reputation as the "Busby Berkeley of the acid set".

[1] Born in Chicago, Illinois, O'Horgan was introduced to theater by his father, a newspaper owner and sometimes actor, who took him to shows and built him footlights and a wind machine.

Those trends, growing partly out of the intimate Off Off Broadway movement and partly out of the visceral political drama of be-ins, sit-ins and demonstrations, include the use of improvisational techniques, vigorous ensemble playing, a more physical style of acting, greater use of dance, music, and puppets, and Pop-camp comedy – plus the Total Theater concept in which the audience becomes more closely involved in the work.

[3] He directed some 50 productions at La MaMa including The Architect and the Emperor of Assyria by Fernando Arrabal, a surrealist play about two men on an island,[6] and Tom Paine by Paul Foster, a recounting of the life of the US Revolutionary War figure.

He first directed the play off-off-Broadway for La MaMa in March 1967 and later took it to the Edinburgh Festival and then to New York's Theater de Lys, an off-Broadway venue in June 1968.

Pepper's Lonely Hearts Club Band on the Road, played at the Beacon Theatre concert venue on Manhattan's Upper West Side.

The production, developed in collaboration with Hair set designer Robin Wagner, featured 34 actors performing 29 Beatles songs with elaborate scenery, special effects and colorful costumes.

[11] Among O'Horgan's other off-Broadway credits include the Second City revues at the Village East To the Water Tower, When the Owl Screams, and The Wrecking Ball as composer, as well as Masked Men (at the Westbeth Theatre) and Birdbath as director.

"[3] In rehearsals, he used techniques passed down by Viola Spolin and Paul Sills of improvisational "games" and role playing theories that encouraged freedom and spontaneity.

[1][10] O'Horgan said that the experience gave him the opportunity to help create "a theater form whose demeanor, language, clothing, dance, and even its name accurately reflect a social epoch in full explosion".

[20] That same year O'Horgan would also direct the 1971 Andrew Lloyd Webber musical Jesus Christ Superstar that became popular with audiences and that, like Hair, would later be made into a movie.

Superstar was notable for the performance of Ben Vereen as Judas Iscariot[21] – whom O'Horgan directed previously on Broadway in the role of Hud in Hair.

"[22] Additional Broadway directing credits include the Tony Award-winning Inner City (1971), a musical conceived by O'Horgan based on controversial poetry book The Inner City Mother Goose by Eve Merriam;[23] the musical Dude (1972), written by Hair author Gerome Ragni with music by Hair composer Galt MacDermot; The Leaf People (1975), a Joe Papp-produced play by Dennis Reardon depicting the first contact by white men with a hostile tribe of Amazonian Indians;[24] and I Won't Dance (1981), a murder whodunit play by Oliver Hailey.

[2][26] O'Horgan directed and composed the score for the screen adaptation of Futz with Frederic Forrest, Sally Kirkland, and Jennifer O'Neill, and directed the film version of Eugène Ionesco's Rhinoceros starring Zero Mostel, Gene Wilder, and Karen Black (and which featured a score by Hair composer Galt MacDermot).

O'Horgan composed the score for Paul Mazursky's Alex in Wonderland starring Donald Sutherland and Ellen Burstyn.

"[29] O'Horgan lived in a 3,000-square-foot (280 m2) loft in Manhattan at 840 Broadway (at 13th Street) that was famous for parties and events attended by artistic figures like Norman Mailer and Beverly Sills.

[31][citation needed] He and his friends rang in many a New Year there, where at midnight everyone would take an instrument off the wall, or find a drum or a gong, and celebrate with an abandon and joy that O'Horgan so often set the stage for (both personally and professionally).

[citation needed] Tom O'Horgan was the initial representation of a father figure to one underaged John Galen McKinley, aka.

It was Tom O'Horgan with whom young and handsome McKinley found not just lodging but also homosexual love after arriving alone and virtually broke in New York's Greenwich Village.

It was before Tom O'Horgan even set foot on Broadway and just started producing experimental plays in his Lower East Side loft and at Ellen Steuart's emerging Cafe La Mama, that McKinley was tending to the technical aspect of theater and learning the basics of stage managing.

At that time O'Horgan, McKinley, and Harvey Milk became an indivisible trio: the teenaged high school dropout, the avant-garde director, and a Wall Street businessman.

[32] He came under the care of friends Marc and Julia Cohen, his loft and collections of instruments were sold, and he moved to Venice, Florida, where he died on January 11, 2009.