William J. Kountz Jr. (October 1, 1867 – August 18, 1899) was an American businessman and an early football player and manager for the Allegheny Athletic Association.

Kountz Jr. attended the Chester Military Academy (now Widener University) for two years before joining the Nicola lumber firm as a traveling salesman.

"[2] In addition to playing guard, Kountz served as Allegheny's manager in 1892, the season in which the team fielded the first recorded professional football player, William "Pudge" Heffelfinger.

However, on the day of the rematch between the two clubs, Heffelfinger, Sport Donnelly, and William C. Malley of the Chicago Athletic Association Football team appeared in the Allegheny line-up.

[7] The stories, each in the form of a letter written by "Billy Baxter" in a slangy style to his friend "Jim",[7] were immediately and widely popular; Rollin Lynde Hartt wrote 20 years later that "no other humorist ever jumped into national fame so abruptly.