Ryan had brown hair, was 5 feet, 2 inches tall, and weighed 107 pounds. A 1940 newspaper story included her in a group of actresses “whose alluring curves alone might have disqualified them from screen careers not so long ago,” in the words of Travis Banton, a Hollywood stylist. Born as Katherine Elizabeth McLaughlin in Topeka, Kansas, she went to Hollywood in 1939 at the age of 18. Her acting career began when she tried out for a role on a program at television station W6XAO (later KCBS) in Los Angeles, California. An article in a contemporary magazine reported, “She proved to be a perfect television type and was given a role at once.” At age 19, Ryan was selected by a group of Hollywood directors as one of 13 “baby stars of 1940.” She was signed by 20th Century Fox in 1940 and was credited in her early films as Bettie McLaughlin. Adopting the name Sheila Ryan, she starred in the crime drama Dressed to Kill the following year. Ryan appeared in other memorable films, including two Laurel and Hardy movies, Great Guns (1941) and A-Haunting We Will Go (1942), and the Busby Berkeley musical The Gang’s All Here (1943). Ryan also was featured in several Charlie Chan and Michael Shayne mysteries. By the late 1940s, however, her career waned and she began appearing mostly in B movies, especially low-budget westerns. In 1945, she married actor Allan Lane (star of western movies and the voice of Mr. Ed), but the marriage ended in divorce after a few months. She worked with Gene Autry, co-starring in several of his films, including The Cowboys and the Indians (1949), and Mule Train (1950) as well as with Roy Rogers in films like Song of Texas. She also had roles in several television shows such as The Lone Ranger, notably the Pete-and-Pedro episode (#7 in 1949) and another entitled “The Whimsical Bandit” in 1950.

Ryan was married first to Edward Norris, but they divorced. Ryan then married actor Allan Lane in 1945, but divorced him a year later in 1946. While working with Autry, Ryan met actor Pat Buttram. They married in 1952 and remained together until her death in 1975. They had a daughter, Kathleen Buttram, nicknamed Kerry. Sheila Ryan retired from acting in 1968. She died in the Motion Picture Hospital in Woodland Hills, California from lung disease. She was 54 years old. She was survived by Buttram and their daughter Kerry. Their daughter Kerry Buttram-Galgano died of cancer in 2008.