William A. Brady left his mark in both boxing, as the only person to manage two undisputed heavyweight champions (James J. Jeffries and James J. Corbett), and in theater, as a Broadway mogul who produced more than 260 plays and managed the likes of Helen Hayes, Douglas Fairbanks, Sr., and Tallulah Bankhead. This first-ever biography, based largely on contemporary sources, places Brady's long life and varied career in context, delving into the formative years of gloved boxing and the rise of 20th-century American theater.