This page lists all of the regulars and recurring cast members on the I Love Lucy TV series.
- Lucille Ball as Lucille Esmeralda "Lucy" McGillicuddy Ricardo
- Desi Arnaz as Enrique Alberto Fernando y de Acha "Ricky" Ricardo III
- Vivian Vance as Ethel Mae Roberta Louise Potter Mertz
- William Frawley as Frederick "Fred" Hobart Mertz
- Richard Keith (aka Keith Thibodeaux) as Enrique Alberto Ricardo IV ("Little Ricky")
- Twins Mike Mayer and Joe Mayer both played "Little Ricky" as a toddler
- Kathryn Card as Minnie Finch ("Fan Magazine Interview") and later as Mrs. McGillicuddy — Lucy's mother
- Mary Jane Croft as Lucy's socialite school chum Cynthia Harcourt, Evelyn Bigsby ("Return Home from Europe") and later as Connecticut neighbor Betty Ramsey
- Frank Nelson as various characters and as Ralph Ramsey
- Jerry Hausner as Jerry, Ricky's agent
- Doris Singleton as Carolyn Appleby (she was originally named Lillian Appleby; but after Singleton's first appearance on the show, the producers felt that the names Lillian and Lucy sounded too similar, so her name was changed to Carolyn)
- Shirley Mitchell as Marion Strong, a role originated by Margie Liszt
- Elizabeth Patterson as Mrs. Matilda Trumbull also the town mayor in the episode "The Marriage License"
- Charles Lane as various characters
- Barbara Pepper as various characters
- Eve McVeagh as Roberta, Lucy's hairdresser
- Bob Jellison as Bobby the Bellboy (Hollywood Episodes)
- Mary Wickes as Madame Le Mond, Lucy's ballet teacher
Gale Gordon and Bea Benaderet, supporting cast members on My Favorite Husband, were originally approached for the roles of Fred and Ethel, but neither could accept owing to previous commitments. Gordon did appear as a guest star in three episodes, playing Ricky's boss, Mr. Littlefield, in two episodes, and later in an hour-long episode as a civil court judge. Gordon was a veteran from the classic radio days in which he perfected the role of the exasperated character, as in Fibber McGee and Molly and Our Miss Brooks. He would go on to co-star with Ball in all of her post–I Love Lucy series ("The Lucy Show", "Here's Lucy" and "Life with Lucy"). Benaderet was a guest star in one episode as elderly Miss Lewis, a neighbor of the Ricardos.
Barbara Pepper (later featured as Doris Ziffel in the series Green Acres) was also considered to play Ethel, but Pepper had been drinking very heavily after the death of her husband, Craig W. Reynolds. Her friendship with Ball dated back to the film Roman Scandals, in which both appeared as Goldwyn Girls. She did, however, turn up regularly in bit parts.
Many of the characters' names were after family members or close friends of Lucille Ball's; for example, Marion Strong was one of her best friends and roommate for a time in New York, and also set Lucy and Ricky up on their first date. Lillian Appleby was a teacher of Lucy's when she was in an amateur production on the stage. Pauline Lopus was a childhood friend, Fred was also her brother and grandfather's name. Lucy and Desi had a business manager by the name of Mr. Andrew Hickox, and in the first episode of season 4, called the "The Business Manager" Lucy and Ricky hire a man named Mr. Hickox.