Tom Selleck missed out on the role of Indiana Jones because he was busy doing
the TV series MAGNUM, P.I.

Shirley Temple and W.C. Fields were the first choices for the roles of Dorothy
and the Wizard in the classic MGM film "THE WIZARD OF OZ."

And can anyone imagine Ronald Reagan (the studio's first choice) as Rick
Blaine in the Warner Bros. classic "CASABLANCA"??

Finally, on television, the role of Lt. Columbo was first offered to Bing Crosby(!).

John Travolta was considered for Chicago's 'Billy Flynn'.