I'm talking about classic films where there are at least three or more actors who are known for their contributions to horror or sci-fi films..
For example:
SON OF FRANKENSTEIN(1939)- Boris Karloff, Basil Rathbone, Bela Lugosi and Lionel Atwill.
YOU'LL FIND OUT- Boris Karloff, Bela Lugosi, Peter Lorre.
THE WOLF MAN(1941)- Lon Chaney, Bela Lugosi, Claude Rains, Evelyn Ankers, Patric Knowles.
GHOST OF FRANKENSTEIN(1942)- Lon Chaney, Bela Lugosi, Lionel Atwill, Evelyn Ankers, Dwight Frye.
HOUSE OF FRANKENSTEIN(1944)- Boris Karloff, Lon Chaney, John Carradine, Lionel Atwill, Glenn Strange, George Zucco, J.Carrol Naish, Anne Gwynne.
THE PEARL OF DEATH(1944)- Basil Rathbone, Evelyn Ankers, Rondo Hatton
CREATURE FROM THE BLACK LAGOON(1954)- Richard Carlson, Richard Denning, Whit Bissell
HOUSE OF DRACULA(1945)-Lon Chaney, John Carradine, Lionel Atwill, Glenn Strange, Skelton Knaggs
WEIRD WOMAN(1944)- Lon Chaney, Evelyn Ankers, Anne Gwynne, Elisabeth Russell.
VOODOO MAN(1944)- Bela Lugosi, John Carradine, George Zucco.
THE BLACK SLEEP(1956)- Bela Lugosi, Basil Rathbone, Lon Chaney, John Carradine, Tor Johnson.
ABBOTT & COSTELLO MEET FRANKENSTEIN(1948)- Bela Lugosi, Lon Chaney, Glenn Strange.
FRANKENSTEIN MEETS THE WOLF MAN(1943)- Lon Chaney, Bela Lugosi, Lionel Atwill, Patric Knowles, Dwight Frye
THE MUMMY'S GHOST(1944)- Lon Chaney, John Carradine, George Zucco
THE UNEARTHLY(1957)- John Carradine, Tor Johnson, Allison Hayes.
and a few more modern ones:
MADHOUSE(1974)- Vincent Price, Robert Quarry, Peter Cushing
CURSE OF THE CRIMSON ALTAR(1968)- Christopher Lee, Boris Karloff, Michael Gough, Barbara Steele.
THE RAVEN(1963)- Vincent Price, Peter Lorre, Boris Karloff, Hazel Court
TWICE-TOLD TALES(1962)- Vincent Price, Richard Denning, Beverly Garland
THE GORGON(1964)- Peter Cushing, Christopher Lee, Barbara Shelley
CURSE OF FRANKENSTEIN(1957)- Peter Cushing, Christopher Lee, Hazel Court
HORROR OF DRACULA(1958)- Peter Cushing, Christopher Lee, Michael Gough
SCREAM AND SCREAM AGAIN!(1969)- Vincent Price, Peter Cushing, Christopher Lee
Can anyone else name more? They are certainly out there..
The Hound of the Baskervilles (1939): Basil Rathbone, Nigel Bruce, John Carridine, Lionel Atwill.
House of Frankenstein
Comedy of Terrors: Basil Rathbone, Peter Lorre, Boris Karloff, Vincent Price
Tales of Terror: Peter Lorre, Vincent Price, Basil Rathbone
House of the Long Shadows: Vincent Price, John Carradine, Christopher Lee, Peter Cushing (very hard to get apparently. Never seen it)
THE OLD DARK HOUSE.. Boris Karloff, Ernest Thesiger, Charles Laughton, Gloria Stuart (James Whale)
ONE MORE RIVER...Colin Clive, Frank Lawton, E.E. Clive, Lionel Atwill (James Whale)
DAVID COPPERFIELD...Frank Lawton, Elizabeth Allan, Basil Rathbone and Violet Kemble Cooper
THE ADVENTURES OF ROBIN HOOD...Basil Rathbone, Una O'Connor, Claude Rains, Lionel Belmore and Patric Knowles