Dennis Webster DeConcini (born May 8, 1937, in Tucson) is a former Democratic Senator from the state of Arizona in the United States, serving from 1977 to 1995.

He was a graduate of the University of Arizona and attended law school there. He worked as a lawyer from 1963, as a memeber of the Arizona Governor's staff 1965-1967 and as Pima County attorney 1973-1976. He was elected to the Senate in 1976, defeating Sam Steiger for the open seat left by retiring Senator Paul Fannin (R-AZ), and served until he retired.

Primarily remembered as a member of the Keating Five, a banking and political contribution scandal in the 1980s which involved Savings and Loans institutions.