Xavier High School is a private Catholic secondary school in Appleton, Wisconsin, United States, in the Diocese of Green Bay.

The school was named in honor of St. Francis Xavier, the patron saint of the Green Bay Diocese.

In November of 2024, Xavier principal Mike Mauthe was fired in the wake of a complaint to the Diocese Office of Safe Environment about a failure to comply with the Diocese of Green Bay’s “Our Promise to Protect” policy.

(A report was filed with the Appleton Police Department, as required by the state's mandatory reporting laws.)

As a result of the investigation into Mauthe, John Ravizza, superintendent of the Diocese' St. Francis Xavier Catholic School System of which the high school is a part, was terminated "because of a failure to meet reporting requirements".