Beach was born and raised in Alexandria, Virginia, and came from a family that was decidedly un-showbiz: his father was a painter and his mother was a housewife. But when 11-year-old Gary saw a traveling performance of “The Music Man,” starring Forrest Tucker, he was amazed. In high school, he acted in plays and joined a theater group called Thespians Troop 1899. Enrolling in college at Old Dominion in Norfolk, he originally planned to major in political science, until a magazine article about the North Carolina School of Arts caught his attention. In no time, he changed his mind, his school and his career. Beach acted primarily in theaters for years. Unlike some actors, he enjoyed lengthy stage runs, with over 1,000 performances combined of “Annie,” “Les Miserables,” and “Beauty and the Beast.” In that stage version of the Disney animated story, Beach played the candelabra, Lumiere, for which he earned a Tony nomination in 1994. He also enjoyed more than 800 performances of “1776,” the show with which he made his Broadway debut. During that memorable run on the Great White Way, Beach's sporadic big screen appearances include Albert Brooks’ “Defending Your Life,” in 1991 and the cult indie favorite, “Man of the Century,” in 1999.

After nearly 20 years in New York City, Beach was eager for a change of pace, and he moved to Los Angeles, where he made a handful of appearances on television, in shows such as “Kate & Allie” and “Murder She Wrote” (CBS) and “Cheers” and “The John Larroquette Show” (NBC). He also made later appearances on “Will & Grace” (NBC) and “Queer as Folk” (Showtime). But he was Broadway-bound again when the call came to play "The Producers'" cross-dressing de Bris in 2000, creating such memorable comic frission with his sidekick Carmen Ghia, played by Roger Bart that, after the musical became a bona fide sensation, both actors were drafted to reprise their roles in the 2005 feature film.