Born Gustave Ferdinand Klotz, on October 7, 1868 in Toledo, Ohio, Gus was the fifth child of John and Louise Klotz, owners of a hotel who catered to theatrical groups.

At 15, Gus left home for New York and found work in a poolroom setting up balls and doing his juggling act. After pressure from his father to learn a "useful trade" he went to work as an apprentice mechanic in a sewing machine factory but continued his art of juggling at night. Gus finally got his break and performed in a variety of traveling shows and circuses, then organized the Sun Brothers United Shows and Trained Animal Exhibition with his brothers. Known as the "Largest Wagon Show on Earth" they toured the country for many years.

In 1904, Gus moved to Springfield and opened the Old Orpheum, combining vaudeville and motion pictures, showing 3-5acts daily. In 1908, he built the New Sun Theater, and opened several other theaters. By 1908 Sun was booking acts into 50 theaters, including Walter Huston, George Burns and Gracie Allen, and Fanny Brice. By 1920, Sun's business deals with other vaudeville circuit managers increased the number of Sun-affiliated theaters to 275.

When the "talkies" came, Sun was forced to close some of his theaters and started booking acts in carnivals and fairs. The August 11, 1926 issue of Variety was devoted entirely to the success of Gus Sun His worth was estimated at several million. He had become an entertainment institution. On October 1, 1959, the renowned showman died.

Gus Sun is buried in Ferncliff Section O, Lot 154 beside his wife, Nellie Alfrey.