An amusing "game" to play is to follow one's "academic ancestors" back through the line of Ph.D. advisors. Dr. Clarke's advisor was Dr. Robert Constable at Cornell (advisor, also, to Dr. Cleaveland and to Dr. Robert Harper, who is an excellent teacher--I took his CS 15-814: Type Systems for Programming Languages my first semester at CMU, and am (as I write this) a Teaching Assistant for his 15-312: Programming Languages). Constable's advisor was Stephen Cole Kleene (of Kleene-* fame). Kleene's advisor was the great Alonzo Church (hooray for the lambda calculus!). Church also advised a fellow named Alan Mathison Turing (as well as Raymond Smullyan, who wrote many books that I have enjoyed...) We then proceed backwards to Church's advisor, Oswald Veblen and, before him, Eliakim Moore, a Skull and Bones member at Yale. Moore's advisor was Hubert Anson Newton (1830-1896, Yale, B.S. in Math 1850), who had no thesis.
My officemate, Seán Slattery, can trace his academic lineage back to Gauss!