Charles Ernest "Chuck" Grassley (born September 17, 1933) is the senior United States Senator from Iowa. A conservative Republican, he has served in the Senate since 1981. From 1958 to 1974, he was an Iowa state legislator. Thereafter he served three terms as a member of the United States House of Representatives. He has twice held the chairmanship of the Finance Committee, from January to June 2001 and from January 2003 to December 2006; as of April 2009, he is the committee's ranking minority member.

Grassley was born in New Hartford, Butler County, Iowa to Ruth Corwin and Louis Arthur Grassley, and graduated from the town high school. At Iowa State Teachers College (now the University of Northern Iowa) he earned a B.A. in 1955 and an M.A. in 1956. He also completed some doctoral studies in political science at the University of Iowa. Also during the 1950s, Grassley farmed and worked in factories, first as a sheet metal shearer and then as an assembly line worker. Grassley married Barbara Ann Speicher in September 1954; the couple have five children: Lee, Wendy, Robin, Michele, and Jay. Grassley is a member of The Family, the Christian political organization that organizes the National Prayer Breakfast.

Grassley represented parts of Butler County in the Iowa House of Representatives from 1959 until 1974, when he was elected to the United States House of Representatives, where he served three terms. He was elected to his Senate seat in 1980, defeating the Democratic incumbent, John Culver. Grassley was reelected in 1986, 1992, 1998, and 2004. As of August, 2009, he is 10th in seniority in the Senate.