Robert "Bob" McCallum Blumenthal (7 February 1931, Chicago – 8 November 2012) was an American mathematician, specializing in probability theory.

[1][2] He received his Ph.D. in mathematics from Cornell University in 1956 under Gilbert Hunt with thesis An Extended Markov Property.

This subject was to become one of the main topics of research in probability for the next 20–25 years.

Already in his thesis Bob had established two of the basic principles of this topic: the strong Markov property (also established independently and more or less simultaneously by Dynkin and Yushkevich in the Soviet Union) and the quasi-left continuity of the sample paths of the process.

[1]Blumenthal became in 1956 an instructor at the University of Washington, was eventually promoted to full professor, and in 1997 retired there.