Born into a family of entertainers, Harold Linn Costello was the older brother of the renowned film comedian Lou Costello. As a stuntman and actor, he frequently doubled for his brother in numerous Abbott and Costello films, showcasing his versatility and talent.
Notably, his most significant on-screen role was that of a plain-clothes policeman in the classic Abbott and Costello film "Mexican Hayride" released in 1948. This iconic role demonstrated his ability to take on a variety of characters and excel in his performances.
What's more, Harold Linn Costello outlived his younger brother Lou by over thirty years, leaving a lasting legacy in the world of entertainment.