Donald (H.S.M.) Coxeter, 2001
Coxeter, one of the most distinguished geometers of the 20th century. I took four classes from him at the U. of Toronto in the 1960s. Although not my supervisor, his work on reflection groups deeply affected my own mathematical life. Here he is photographed lecturing in Banff at conference set around my 60th birthday. This was the last time I saw him.