Pick one category for the following text. The options are - company, educational institution, artist, athlete, office holder, mean of transportation, building, natural place, village, animal, plant, album, film or written work. Mysterious Walker -  Frederick Mitchell Walker (March 21 1884 – February 1 1958) nicknamed Mysterious was an American athlete and coach. He was a three-sport athlete for the University of Chicago from 1904 to 1906 and played Major League Baseball as a right-handed pitcher for the Cincinnati Reds Cleveland Indians Brooklyn Superbas Pittsburgh Rebels and Brooklyn Tip-Tops.He earned the nickname Mysterious after pitching under a pseudonym for the San Francisco Seals of the Pacific Coast League in 1910.
The answer to this question is:
Athlete