William J. Ryczek is a banker and writer who has written a number of baseball books. He has written When Johnny Came Sliding Home (1998) about baseball in 1865-1870, and Blackguards and Red Stockings (1992) about the National Association from 1871-1875. He also wrote The Yankees in the early 1960s (2008).
In 2009 his book Baseball's First Inning appeared, about baseball through 1865.
He has also written at least one football book, under the name Bill Ryczek.