Willie Frank Zapalac Jr. (born September 1, 1948) is a former American football linebacker and defensive end in the National Football League (NFL).

Zapalac attended the University of Texas and played college football for the Longhorns. Zapalac was a 3-time academic all-conference and twice was named Academic All American in 1969 and 1970. In 1970, he was elected as one of the four captains and was named to the National Football Foundation Academic All American team. Zapalac started 33 straight games while playing 3 different positions on Texas teams that had a combined record of 30–2–1. He graduated from the school of Architectural Engineering with Honors. In 2011, he was inducted in the University of Texas Hall of Honor.

Zapalac was a 4th round selection (84th overall pick) in the 1971 NFL draft by the New York Jets. He played for three years with the Jets (1971–1973).

Since retiring from football, Bill has worked in the construction industry since 1974. For the past 28 years he has been president of Zapalac/Reed Construction in Austin, Texas. University of Texas 2023 Distinguished Alumni of Civil, Architectural, Environmental Engineering department.

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