Turned down Cary Grant's role in The Philadelphia Story (1940) because he was eager to make Dr. Jekyll and Mr. Hyde (1941).
Turned down the role of the judge in Anatomy of a Murder (1959), Edward Arnold's role in Come and Get It (1936), Michael Rennie's role in The Day the Earth Stood Still (1951), Desi Arnaz's role in Forever, Darling (1956), William Powell's role in Mister Roberts (1955), Donald Crisp's role in National Velvet (1944), Melvyn Douglas's role in Ninotchka (1939), and Gregory Peck's role in The Yearling (1946).
Warner Bros. bought the rights to the book "Mute Witness" about a Boston detective who ate a lot of ice cream and never solved a case with Tracy in mind to star. Upon Tracy's death, a chase scene was added to the script, the location changed to San Francisco, and the character - Detective Frank Bullitt - changed to be played by Steve McQueen.
Was seriously ill with emphysema as well as diabetes when he made his final film Guess Who's Coming to Dinner (1967).
Was supposed to star in Ten North Frederick (1958), but had to withdraw due to poor health and was replaced by Gary Cooper.
When he needed a break, he would often come back to Milwaukee and frequent the local watering holes. However, finding him proved to be an almost impossible challenge for Katharine Hepburn, because there are so many bars in Milwaukee.