Roy Halladay, star pitcher for the Blue Jays and Phillies, also ran XC in high school.
http://www.jockbio.com/Bios/Halladay/Halladay_bio.html
This article says he placed third at the Colorado State meet. I've been trying to find some official results, does anyone know of any times or anything? Or is this another rumor of a famous person running fast?