Originally from Nebraska, Stull started out acting with stock companies. By 1894 he found himself in Philadelphia (a fortuitous base of operations), performing with the Forepaugh Stock Company. In Philly he became a local matinee idol, starring also with the Girard Avenue Theatre, then touring nationally with several companies, including his own Walter H. Stull Stock Company.
In 1911 he made his first film with the Philadelphia based Lubin Manufacturing Company, A Hero — Almost. He was to appear in no fewer than 162 films over the next nine years. Around 100 of these were Pokes and Jabs comedies, made between 1915 and 1917. Stull and Burns had appeared in many films together prior to the former teaming. Unlike many comedy pairs, the two were undifferentiated in appearance, but, true to their name, they built every comedy to a payoff of fisticuffs. These were made by the Vim Comedy Comedy, Jacksonville, Florida, which had bought up Lubin South in 1915.
After Pokes and Jabs played out, Stull teamed with Billy Ruge for a series of five Finn and Haddie comedies for a company called Jaxon (presumably because it was based out of Jacksonville, Florida) in 1918. Stull also directed 65 comedies starting in 1915, most of them Pokes and Jabs pictures. According to IMDB, his last film credit was the co-direction, with Burns, of the 1920 Hank Mann comedy Way Out West.
For more on silent screen comedy please read Chain of Fools: Silent Comedy and Its Legacies from Nickelodeons to Youtube.