A ProfessorEmeritus? in the math department, but he is around frequently. His specialty is probability theory.
ProfessorKrieger has an awesome beach house that he invites the MathClub? to come hangout at. When the MathClub? went in 2007, he had a large probability book sitting on his chair that he appeared to be reading for fun.
On the down side, he's deaf.
Is the opposite of the "deaf older person" stereotype: rather than talking very loudly, he will talk very very quietly.