William "Bill" Casper was born on January 29, 1931, on a farm on the east shore of Lake Winnebago in Taycheedah, Wisconsin. He has spent his entire life in this area, except for four years during the Korean War. Casper grew up on the family farm, which he continued to be associated with throughout his life. He was introduced to hunting and fishing at an early age by his uncles, particularly Ambrose Langenfeld, who played a significant role in shaping his interest in sturgeon spearing. At the age of 14, Casper speared his first sturgeon.

William Casper was born in Wisconsin and grew up in a rural area near Lake Winnebago. He developed an interest in fishing at a young age, encouraged by his uncles. Casper's career began at Giddings & Lewis, a machine shop in Fond du Lac, where he worked as a machinist and eventually became a maintenance foreman. His passion for fishing, particularly sturgeon spearing, led him to become an advocate for the conservation of the species.