James E. "Jim" Kreuser (born May 20, 1961) is an American politician and former County Executive for Kenosha County, Wisconsin, serving from 2008 to 2022. A member of the Democratic Party, he previously represented Kenosha in the Wisconsin State Assembly for 15 years (1993–2008) and was the Assembly Minority Leader from 2003 through 2008.

James Kreuser was born and raised in Kenosha, Wisconsin. He graduated from George Nelson Tremper High School in 1979 and earned his bachelor's degree in political science from Kenosha's University of Wisconsin–Parkside in 1983. He continued his education at Parkside and received his Master's in Public Administration in 1986.

During his time at Parkside, Kreuser interned with Kenosha County Executive, John Collins, and, after completing his M.P.A., was hired as a full-time administrative assistant in the county executive's office. Kreuser later credited the experience he received working in the county executive's office, getting to know the county and state government, with enabling his success as a legislator.

He was still working for the county executive when, in 1993, a chain of events—starting with the appointment of local-area congressman Les Aspin to join the cabinet of newly inaugurated President Bill Clinton—resulted in a vacancy in the Wisconsin State Assembly district in which Kreuser resided. A special election was called for August 1993, and Kreuser was elected. He topped his two Democratic opponents in the primary, carrying just over 50% of the vote, then defeated his Republican general election opponent, William F. Cantwell, by a wide margin.

Kreuser went on to win re-election seven times, receiving attention and praise from his colleagues as an up-and-coming leader in the party. Senate Majority Leader Charles Chvala was quoted as saying Kreuser was, "destined to be a leader." He made his first bid for leadership in the Assembly Democratic caucus in the summer of 1998, when long-time Democratic leader Walter Kunicki stepped down from the role. Despite strong support from a geographically diverse coalition of the assembly, Kreuser fell one or two votes short of Milwaukee representative Shirley Krug, who became the first female caucus leader in state history.

In 2001, amid discontent within the caucus over the results of the 2000 election, Kreuser made a successful bid with Assistant Minority Leader Spencer Black of Madison, to challenge Krug as floor leader. Black was elevated to Minority Leader and Kreuser was elected as Assistant Minority Leader, in what was seen as a repudiation of the Democratic Leadership Council in Wisconsin.

Black stood down as leader at the end of the 2001-2002 term, and Kreuser was elected just after the 2002 election as the next Minority Leader. Over his three terms as minority leader, Democrats increased from 41 seats in the Assembly to 47.

In March 2008 another opportunity presented itself to Kreuser when Kenosha County Executive Allan Kehl announced his intention to resign his seat after being indicted for accepting illegal payments. Kreuser quickly jumped into the race, announcing his candidacy on March 25, 2008, and won the special election without opposition in June. At the time he announced his candidacy, he pledged not to run for re-election to the Assembly if he was chosen as County Executive.