An expert on biological weapons, she emerged as an influential voice during the F.B.I.’s rocky search for a suspect after the deadly anthrax attacks of 2001.

An activist in the academy, he wrote a foundational text in the field, “Occupied America: A History of Chicanos.” It is still in print and still assigned to students.

The Hollywood star was an unusually hands-on activist and donor, whose deep understanding of politics set him apart from other celebrities.