Sigh.
The "Duke" started in film in the 1920's, just as a point of reference. And he played that one character really well.
Source: U.S. Department of Labor, Bureau of Labor Statistics;
http://www.bls.gov/oco/ocos093.htm#trainingTRAINING, OTHER QUALIFICATIONS, AND ADVANCEMENT
Formal dramatic training, either through an acting conservatory or a university program, generally is necessary, but some people successfully enter the field without it. Most people studying for a bachelor’s degree take courses in radio and television broadcasting, communications, film, theater, drama, or dramatic literature. Many continue their academic training and receive a Master of Fine Arts (MFA) degree. Advanced curricula may include courses in stage speech and movement, directing, playwriting, and design, as well as intensive acting workshops. The National Association of Schools of Theatre accredits 135 programs in theater arts. A few people go into acting following successful careers in other fields, such as broadcasting or announcing.
Some actors you might have heard of: (Oscar winners and nominees in bold, I didn't feel like searching out Emmys and Tonys)
Susan Sarandon - Undergrad – Catholic School of America
Tim Robbins - SUNY Plattsburg, UCLA Film School
Denzel Washington BA in Drama and Journalism Fordham University, Graduate work – American Conservatory Theatre
Forrest Whitaker – Univ of Southern CA (opera) Drama Studio London (UC Berkley)
Judy Dench – Central School of Speecha dn Drama – London,
Meryl Streep – Yale School of Drama
Some alumni lists from different schools:
North Carolina School of the Arts
Alumni: Diedrich Bader, K. Todd Freeman,
Tom Hulce , Mary-Louise Parker, Jada Pinkett Smith
Southern Methodist Univ. Alumni:
Kathy Bates (BFA), Powers Booth(MFA),
The Actor’s Studio Alumni –
Marlon Brando, Robert DeNiro (also attended the Stella Adler School), Norman Mailer, Eli Wallach,
Sidney Poitier,
UCLA
Corbin Bernson, Jack Black , Carol Burnett,
James Dean, Joyce DeWitt, Mariska Hargitay, Mark Harmon,
Tim Robbins, Tom Skerritt, George Takei,
Tisch School of the Arts NYU Alumni – Barry Bostwick, Peter Krause, Eriq LaSalle, Debra Messing,
Royal Academy of the Dramatic Arts:
Peter O’Toole, Richard Attenborough, Alan Bates, Sean Bean,
Kenneth Branagh, Michael Caine, Timothy Dalton, Brian Epstein, Ralph Finnes,
Albert Finney, John Gielgud, Ian Holme,
Anthony Hopkins,
Trevor Howard,
John Hurt,
Glenda Jackson,
Vivien Leigh, Joan Littlewood, Roger Moore, Alan Rickman, Fiona Shaw
Needless to say this is just hte tip of the iceberg. Yes you can make it in film and television without going to college, on stage it is much tougher. Longevity - training helps.