Billy Lee, whose real name was William Schlensker, was born in Nelson, Indiana. As a toddler, young William lived a quiet life on his family's farm, but that all changed when he turned three years old. Billy and his parents moved to California around 1933. Billy's parents enrolled him, at age 3, in The Meglin School For Kiddies in Los Angeles. The supervisor of the school, Ethel Meglin, took a special interest in Billy Lee, noting, as his parents had, that Billy was a very bright and cooperative child, quick to learn and full of enthusiasm. Mrs. Meglin, who was Billy's personal dance instructor, got Billy Lee started in movies by age 4, only a few months after he was enrolled at the school. Billy's first role was in a "Little Rascals" short, "Mike Fright," as himself (as a tap dancer), and he gives quite an impressive example of his talent. From there it was on to Billy's first feature film, "Wagon Wheels" (1934), wherein Billy landed his first acting role, which his dance instructor, believing in his talent, had him audition for. Billy also has a solo singing part in the movie. This takes place when the primary cast, including Randolph Scott, takes turns singing lead on the movie's theme song. So it was that, at age four, young William went from being a young Indiana farm boy to Billy Lee, young Hollywood actor. In 1937, Billy Lee appeared with famous child singer Bobby Breen in Make a Wish (1937), playing Breen's best camp buddy, "Pee Wee." The two boys sang "Polly Wolly Doodle" as a duet. Billy may be best known for his starring role in the very moving 1940 movie The Biscuit Eater (1940). He continued acting throughout the 1930s, appearing in over 30 movies and working alongside some of Hollywood's finest, including Lon Chaney Jr., Roy Rogers, Charles Boyer, Randolph Scott, Olivia DeHavilland, and Broderick Crawford, to name just a few. Billy also appeared in a few short subjects. One Hal Roach short in particular cast Billy, now age 11, in the starring role of "Pinhead" in the 1941 musical comedy film Reg'lar Fellers (1941) along with Carl "Alfalfa" Switzer as "Bump." The characters in this film were based on the popular "Reg'lar Fellers" comic strip. This film not only provided Billy with a chance to play in a lead comedic role but also allowed him to show off his drumming skills during one musical number that had been recorded by "Billy Lee's Band" according to the credits. In the film, Billy is joined by other young musicians playing accordion, trumpet, trombone and xylophone, performing as Pinhead's band. Billy also sings the closing song of the film, "Hooray For Fun."

Another short in which Billy landed the lead role was called War Dogs (1942) (aka "Unsung Heroes"). Billy plays the doting son of his aging, decorated military officer dad, who has turned to drink after his request to rejoin the service to help in the war effort (WW2) is turned down by the military. Billy's last film appearance came in 1943, when he was 13 (surprise, surprise) in a movie called, Eyes of the Underworld (1942) in the role of Mickey Bryan, devoted son of police chief Richard Bryan, played by Richard Dix. After this film, Billy Lee' father moved the family back to Indiana.

Billy Lee continued on as a guitarist, playing gigs locally. and as soon as he was of age, he joined the Armed Services.

Billy Lee lived until 1989; he died eight months after his 60th birthday of a sudden heart attack.