William Dennes (1898-1982) was an American philosopher.
Dennes arrived as a philosophy professor at the University of California, Berkeley in 1923. Shortly thereafter he established himself as an academic leader, and soon became the chairman of the department. He would hold that office until his retirement in 1965.
In the meantime his colleague at Berkeley, J. Robert Oppenheimer, was impressed by his administrative skills and invited him to Los Alamos to be the Assistant Director of the Manhattan Project. However, this association would be a brief one, as the difference in the two men’s temperaments proved too difficult to negotiate. Dennes was also reluctant to leave his two teenage children in Berkeley for a substantial period of time.