Born January 16, 1933, in Cleveland, Ohio, he began writing cartoons for the Cleveland Press. After that, he moved on to Hollywood, California and continued his writing career with work on Get Smart. Then, in 1968, he won an Emmy for his work on Rowan & Martin's Laugh-In. Following this, he moved on to Marcus Welby, M.D., The Sonny & Cher Comedy Hour, Police Woman, The Waltons, and CHiPs. In the 1980s and '90s, he worked on a scattering of television shows and movies, including co-writing the Super Mario World episode "The Wheel Thing" and serving as one of four writers for the second season (1985–86) of the cartoon series Inspector Gadget, as well as writing & co-writing shorts for the 1980 revival of Tom & Jerry. Hanrahan teamed-up for a while with Eleanor Burian-Mohr and wrote for many animation shows. He also co-starred in the motion picture 'Up Your Alley' in 1988 for writer/director, Bob Logan.
Hanrahan left Beverly Hills for Eureka in northern California in 1992. After losing his wife in 2004, he was stricken with grief. He would still entertain at charity events and retirement homes but never found his way back to happiness. In 2006, he was evicted following a garage fire and all of his possessions, including his Emmy, were seized by his landlord. He began to wander the streets. Jack Riley, an old friend, tried to help Hanrahan, but was unsuccessful.
After friends in Eureka bought him a bus ticket, he returned to his hometown of Cleveland, where he remained homeless until his death. Hanrahan was featured on the front page of The Plain Dealer (Cleveland, Ohio) on March 22, 2007, detailing his homelessness.
He died on April 28, 2008.
