R
- Henry T. Rainey, politician (Democrat), member and Speaker of the U.S. House of Representatives
- Harold Ramis, actor, director, writer, Ghostbusters parts 1 and 2, As Good as It Gets, Analyze This, National Lampoon's Vacation
- Antwaan Randle El, wide receiver for the Pittsburgh Steelers
- Lou Rawls, soul, jazz and blues singer and actor
- James Earl Ray, assassin of Dr. Martin Luther King, Jr.
- Ronald Reagan (1911–2004), actor and politician (Republican), 40th President of the United States, Governor of California
- John C. Reilly, actor; Talladega Nights, Step Brothers, Chicago
- Denise Richards, actress, The World Is Not Enough, Denise Richards: It's Complicated
- Quentin Richardson, swingman for the Orlando Magic
- Salli Richardson, actress, Eureka, Gargoyles, Family Law
- Sy Richardson, actor, Pushing Daisies
- Andy Richter, actor, comedian, writer, Late Night with Conan O'Brien, the Madagascar films & cartoons
- Doc Rivers, former NBA point guard and head coach for the Boston Celtics
- Robin Roberts, Hall of Fame starting pitcher who played primarily with the Philadelphia Phillies
- Craig Robinson, actor, stand-up comedian, The Office, Lucky, Last Comic Standing
- Knute Rockne, College Football Hall of Fame head coach for the Notre Dame Fighting Irish
- George Lincoln Rockwell, founder of the American Nazi Party
- Richard Roeper, columnist, film critic, former co-host of At the Movies
- Carl Rogers, prominent psychologist
- Christina Romer, chair of the Council of Economic Advisers under President Barack Obama
- John Root, architect
- Adam Rosales, third baseman for the Oakland A's
- Derrick Rose, NBA player for the Chicago Bulls
- Julius Rosenwald, businessman and philanthropist, President of Sears, Roebuck & Company
- Ricco Ross, actor, Westbeach
- Larry Rothschild, pitching coach for the New York Yankees
- Rudy Ruettiger, motivational speaker and former collegiate football player for the University of Notre Dame
- Donald Rumsfeld, politician (Republican), Secretary of Defense, White House Chief of Staff, U.S. Representative
- William A. Rusher, lawyer, columnist, publisher of National Review from 1957–1988
- Chuck Russell, director, The Mask, Eraser
- Ann Rutledge, friend of Abraham Lincoln
- Rex Ryan, head coach for the New York Jets
- Robert Ryan, actor
- Shawn Ryan, television producer and writer, The Shield, The Unit, Angel
- Lou Rymkus, NFL tackle and head coach for the Houston Oilers
- Marc Rzepczynski, relief pitcher for the St. Louis Cardinals
Read more about this topic: List Of People From Illinois