O'Halleran, Tom, 1946-

Thomas Charles O'Halleran (born January 24, 1946) is an American politician serving as the U.S. representative for Arizona's 1st congressional district since 2017. Beginning his political career as a Republican, he was the Arizona state senator from the 1st district from 2007 to 2009. In 2015, he became a member of the Democratic Party. He also serves as the chair of communications for the Blue Dog Caucus.

O'Halleran served with the Chicago Police Department from 1966 to 1975. He then became a member of the Chicago Board of Trade, operating his own futures trading business with a focus in futures contracts on 10-year U.S. Treasury notes.

O'Halleran, then a Republican, served in the Arizona House of Representatives from 2001 to 2007. He then served in the Arizona State Senate, representing the 1st district from 2007 to 2009. In a 2008 primary election, he was unseated by Steve Pierce. After leaving the Arizona legislature, O'Halleran hosted a radio show on KAZM in Sedona.

In 2014 he left the Republican Party, citing its policies on education, water, and child welfare.