Chief Illiniwek was the official mascot of the University of Illinois from the 1920s until 2007 when it was retired. The first chief costume was fashioned in 1926 by Lester Leutwiler, a student who drew on his experience as an Eagle Scout and knowledge of Native American folktales and lore to construct a costume and then perform as “the Chief” at University football halftime shows. The Chief appeared at sporting events, mostly football and basketball, as part of the Marching Illini band and danced during halftime. 

The later half of the 20th century brought increasing amounts of controversy surrounding the Chief, as Native American advocacy groups protested the use of a Native American as a mascot. The controversy was most intense during the 1990s-2000s, with both pro- and anti-Chief groups expressing their opinions in political cartoons, editorials, and /demonstrations/protests on campus. In 2005, the NCAA instituted a ban on universities with American Indian nicknames hosting postseason games. This potential hit in revenue finally drove the university to relinquish the Chief Illiniwek mascot in 2007. 

In the years since the controversy began, many alternative mascots have been suggested, including the Tully monster, a robot, and Abraham Lincoln. Currently the University of Illinois' mascot is just "the fighting Illini," which is not intended to refer to the Native American tribe.

Despite the official retirement of the Chief mascot, a new Chief portrayer is selected every few years and appears mostly at non-University events, though he has been spotted at numerous University-sponsored athletic events since the retirement.  

For more information on the history of the "fighting Illini" name/mascot at the University of Illinois, see this University Archives FAQ page.