William "Billy the Killer" Miller (1906 – April 16, 1931) was an American bank robber and Depression-era outlaw. In his brief criminal career, he committed numerous bank heists in Michigan, Ohio, Kentucky and Oklahoma, and teamed up with George Birdwell and Pretty Boy Floyd during the early 1930s.[1][2]

William Miller was born in Ironton, Ohio in 1906. He first earned his nickname "Billy the Killer" when, on September 18, 1925, the 19-year-old Miller killed his brother Joseph in a fight over a woman. Tried in Beaver County, Pennsylvania, he was acquitted of murder on the grounds that he had suffered emotional trauma due to the death of his brother. He eventually fell into a life of crime and, in August 1930, he was arrested by police in Lakeside, Michigan[disambiguation needed] and charged with a series of bank robberies committed in Michigan and Ohio. On September 2, Miller escaped from custody while imprisoned in Lucas County, Ohio and fled to Oklahoma where he eventually joined up with George Birdwell and Pretty Boy Floyd.[1]

On March 9, 1931, he joined Birdwell and Floyd in a $3,000 bank robbery in Earlsboro, Oklahoma. While Miller and Floyd headed for Kansas City shortly afterwards, Birdwell choosing to remain in Oklahoma, and began dating sisters Rose Ash and Beulah Baird. At the time, Rose was married, and Beulah was dating her brother-in-law. On March 25, Miller and Floyd murdered the men, brothers William and Wallace Ash, and left their bodies in a car which was found on the outskirts of town days later. Meanwhile, Rose and Beulah joined the outlaws as they continued their crime spree.[1]