Jack Kleinman was a salesman for the Victory Brush Company in New Jersey. In the late 1930s, Kleinman attempted to enlist in the United States Army, to fight the Nazis, but was not allowed. He expatriated to France where he joined the French resistance, and later went under the name "Jacques S'er."
Kleinman was descended from the legendary Joxer the Mighty. After an encounter with Ares, Kleinman gained possession of the Xena scrolls, keeping them in his attic and translating them out of the original Greek. His grandson, Ted, would later gain possession of them. He also had a crush on Melinda Pappas, flirting with her a lot.