William James Frederick Riordan CBE (8 February 1908 – 15 January 1973) was an Australian politician.

[1] On the death of his uncle Darby Riordan in 1936 he won the subsequent by-election for the Australian Labor Party and held the seat until his retirement before the 1966 election.

[2] Riordan was appointed Minister for the Navy in the Chifley ministry from November 1946 to the defeat of the government at the 1949 election.

Kennedy was a very large electorate, which meant Riordan had to travel constantly to meet his constituents, particularly workers in the sugar, mining and meat processing industries, in order to be re-elected.

After his retirement his seat was won by the Country Party and has been held by Labor for only one parliamentary term since.