Dennis Hastert (John Dennis "Denny" Hastert) (hăs´tərt), 1942–, U.S. congressman, Speaker of the U.S. House of Representatives (1999–2007), b. Aurora, Ill. He attended Wheaton College (B.A., 1964) and Northern Illinois Univ. (M.S., 1967). After teaching high school and serving as a Republican member of the Illinois House of Representatives (1980–86), he was elected to the U.S. House of Representatives in 1986, where he chaired the government reform and oversight committee's subcommittees on criminal justice, international affairs, and national security. A plainspoken, congenial, and popular conservative, Hastert became chief deputy majority whip and won a reputation for integrity, patience, and cautious bipartisanship, which helped him forge political compromises.

Hastert was lifted from relative obscurity in 1999 when the House Republican hierarchy, in search of an uncontroversial and trusted leader to succeed the ideological and pugnacious Newt Gingrich, chose him as Speaker. In office Hastert proved generally to be conciliatory and collegial while nonetheless maintaining tight Republican control over the House legislative process; he was instrumental to the passage of Medicare overhaul legislation in 2003. A number of Republican congressional scandals in 2005–6 hurt Hastert's standing among his fellow House Republicans, and following the party's loss of control of the House in the 2006 elections he announced that he would not seek a leadership post. His term as Speaker was the longest of any Republican. He retired from Congress in 2007.