Carl Sheldon "Cap" Williams (May 16, 1872 – November 8, 1960) was an American football player and coach, and an ophthalmologist.

[1] A Wellington, Ohio, native, he graduated from the University of Pennsylvania in 1894 with a Bachelor of Science and a medical degree in 1897.

[5] He lettered three seasons at quarterback for the Red and Blue under renowned coach George Washington Woodruff.

Before the 1895 season, Walter Riggs a graduate manager for the Auburn Tigers football team, wrote to Williams asking the Penn captain to suggest a suitable coach.

When Williams first arrived he had to deal with a team and athletic department recovering from an undergraduate and dental student revolt that led to Woodruff to resign.

The students were dissatisfied with the team's performance in the 1901 season and demanded more undergraduate say in athletic department and coaching.

In just his third season as head coach, Williams and Penn posted a 12–0 record and the program's fourth national crown.

This Quakers squad has a dominating Defense that only allowed 0.3 points a game with Swarthmore the only school to score on them that season.

[12] The next year Williams led Penn to the second-straight undefeated season posting a 12–0–1 mark.

[19] Penn's fifth and Williams second (as a coach) retroactive national title came after an 11–1 campaign in his last year at the helm of the Quakers.

Williams earned degrees in ophthalmology the University of Heidelberg and London's Royal Ophthalmic College.