Kate Jackson was initially cast as Kelly Garrett but asked to switch to the role of Sabrina Duncan, and her request was granted, while Jaclyn Smith was cast as Kelly after producers liked her on-screen chemistry with Jackson and Fawcett.

The series was originally titled 'The Alley Cats,' with three characters named Allison, Lee, and Catherine who would live in alleys and wear whips and chains, before Kate Jackson pushed for a new title after seeing a picture of three angels in Aaron Spelling's office, leading to 'Harry's Angels' and finally 'Charlie's Angels' once ABC vetoed the name due to the show Harry O.

John Forsythe, who voiced the unseen Charlie Townsend, recorded all his lines in a studio and was never on set, so he rarely met his female co-stars; he only realized how little contact he'd had when Farrah Fawcett approached him at a tennis court saying 'Charlie! I finally met Charlie!'

Forsythe got the role of Charlie in a last-minute panic after original choice Gig Young showed up too intoxicated to read his lines; Spelling called Forsythe late at night, who drove to the studio still in his pajamas under a topcoat to record the part.

An early pilot version included a character named Scott Woodville, played by David Ogden Stiers, added by ABC executives as a male supervisor for the Angels similar to Jim Phelps in Mission: Impossible, but the character was cut after test audiences reacted negatively, with his responsibilities folded into the Bosley character.

ABC executives Michael Eisner and Barry Diller were reportedly so skeptical of the show's premise that Eisner called it 'one of the worst ideas I've ever heard' and Diller claimed no one would watch it; after the pilot scored huge ratings, ABC didn't believe the numbers and re-aired it to confirm, getting the same high results.

Kate Jackson was reportedly offered the role of Joanna Kramer in Kramer vs. Kramer (1979), but producers refused to adjust the Charlie's Angels shooting schedule to let her take it, and the part ultimately went to Meryl Streep, who won an Oscar for it.

Before Shelley Hack was cast to replace Kate Jackson, several rising actresses were considered for the role, including Barbara Bach, Connie Sellecca, Shari Belafonte, Judith Chapman, and a young Michelle Pfeiffer.

A 1976 poster of Farrah Fawcett in a red swimsuit, unrelated to the show itself, became the best-selling poster in history with 12 million copies sold and helped boost the series' popularity; the swimsuit was later donated to the Smithsonian Institution.