Marc Okkonen (1933-2019) was a baseball researcher specializing in the history of uniforms. His book Baseball Uniforms of the 20th Century: The Official Major League Baseball Guide, published in 1991 and illustrated with his own drawings, is the seminal work on the subject.
In addition to this work, Okkonen wrote a series of books entitled Baseball Memories which capture the look and feel of baseball in various past decades, and 2,000 Cups of Coffee, a database of images of ballplayers who only had short major league careers. He is also the author of a pioneering work on the Federal League.
He was honored with the Henry Chadwick Award in 2014.
- Dan Cichalski: "Researcher who made old unis cool passes away: Okkonen's book, 'Baseball Uniforms of the 20th Century,' popularized throwbacks", mlb.com, May 30, 2019. 
- Dan Levitt: "Marc Okkonen", The Baseball Research Journal, SABR, Volume 43, Number 1 (spring 2014), p. 121.