J. L. Doob (27 February 1910--7 June 2004)

Doob’s essential contributions to Probability theory are discussed; this includes the main early results on martingale theory, Doob’s $h$-transform, as well as a summary of Doob’s three books. Finally, Doob’s `stochastic triangle’ is viewed in the light of the stochastic analysis of the eighties.