The Principal Cast
For the Defense
Raymond Burr (IMDb) played the eponymous attorney Perry Mason who never, except sort of a few times, lost a case. Barbara Hale (IMDb) was Perry's very capable private and proper secretary Della Street. These pictures from episodes #25 and #130. I know, that's not the best picture of Barbara Hale. For a few others, look here.
William Hopper (IMDb) was Perry's detective-of-choice Paul Drake, the proprietor of the well-staffed Paul Drake Detective Agency. Connie Cezon (IMDb) was Perry's perky receptionist Gertrude "Gertie" Lade. These pictures are from episodes #199 and #204.
For the State
William Talman Remembrance Page (IMDb) appeared as Perry's most frequent and always defeated adversary District Attorney Hamilton Burger. Ray Collins (IMDb) played the crafty and irascible Police detective Lt. Arthur Tragg. These pictures are from episodes #15 and #71.
After Ray Collin's departure during the 7th season due to illness, the police detective job was filled by Wesley Lau (IMDb) as Lt. Anderson and later by Richard Anderson (IMDb) as Lt. Steve Drumm. These pictures are from episodes #223 and #257.
Other "regular" characters
During the final season, Perry and crew occasionally conducted business at "Clay's Grill," a restaurant run by Terrance Clay, a recurring role played by Dan Tobin (IMDb). Karl Held (IMDb) appeared in 9 episodes as David Gideon, a law student working with Perry. Lee Miller (IMDb), Raymond Burr's stand-in on the set, appeared as Sgt. Brice in at least 57 episodes and, uncredited, in many others. For more recurring characters, see the statistics page.
Name links go to the appropriate section of The Perry Mason TV Show Book.