Longtime Chicago agency fixture and creative executive Jim Schmidt died this week after a battle with cancer. He was 58.

Mr. Schmidt is perhaps best known professionally as co-founder and creative director of Omnicom's Downtown Partners, an offshoot of DDB Chicago founded in 2004. Downtown Partners, run by Mr. Schmidt, Joe Stuart and Katy Baxter, for years handled broadcast advertising for Walgreens, and was more recently known for its work for the Illinois Lottery and the Chicago Convention & Tourism Bureau.

The shop also handled work for Chicago's Lyric Opera and was the lead agency for the Chicago 2016 Olympic Games bid. He also co-wrote and co-directed a documentary on the Olympics bid that ran on PBS and NBC.

Prior to launching Downtown Partners, Mr. Schmidt spent 15 years at McConnaughy Stein Schmidt Brown, another shop he helped launch in 1988, as creative director and partner. In 2000, Havas Worldwide, formerly Euro RSCG, acquired the agency and Mr. Schmidt spent the subsequent three years as Euro's chief creative officer before opening Downtown Partners.

Mr. Schmidt, who lived in suburban Northbrook, Ill., attended Ball State University in Indiana and Columbia College in Chicago. He is survived by wife Cindy and his four children, Lauren, Jimmy, Kathryn and Jack.