Thomas More Prep-Marion is a private Catholic high school located in Hays, Kansas. It is coeducational and serves grades 9-12. Its history dates back to 1908 but the school was officially founded in 1981 when 3 local Catholic schools merged to create it.

Thomas More Prep-Marion is run by the Capuchin Franciscan order. In 2010, it served about 220 students and it boasts a low student / teacher ratio, about 8 to 1, lower than Kansas average. The school colors are white and navy blue and their mascot is the Monarch.

Graduates of this school state that they have benefited greatly from their time at Thomas More Prep-Marion.

Notable Alumni include Jeff Colyer, Lieutenant Governor of Kansas and John L. Allen Jr. an American journalist.