Piggy-backing off of this question, I was thinking today about the women Lucy used on her TV shows.
Of course, we have Vivian Vance, the best second banana in the history of television. Vance was a perfect sidekick for Ball: attractive, capable, and a good actress and physical comedienne. It's no wonder that the two formed a strong off-screen friendship during the production of I LOVE LUCY in the 1950s. Lucy apparently wouldn't agree to do THE LUCY SHOW in 1962 for CBS until Vance agreed to come back as her co-star. Vance agreed, but only on the assurance that her character would be called "Viv" (she was still be called "Ethel" on the street at the time) and that he wardrobe would be more glamorous than what she had on the earlier show. Vance ended up staying with THE LUCY SHOW as Ball's full-time co-star until 1965, when she finally decided to withdrawal from the show as a regular. She appeared as a guest star in the show's final three seasons, and she ended up being practically a yearly guest star on Ball's following series called HERE'S LUCY.
Vivian Vance was Lucy's best TV sidekick. No one was better at countering Lucy's antics.
The next one I always think of is Mary Jane Croft. A television actress, she worked on such sitcoms as THE ADVENTURES OF OZZIE AND HARRIET, I MARRIED JOAN, and OUR MISS BROOKS in the 1950s before meeting and pairing up with Lucy. Croft appeared on I LOVE LUCY as Lucy's old school snotty school chum Cynthia Harcourt and as the nosey Evelyn Bixby, who discovers Lucy's "baby" is actually a block of cheese while flying on an airplane. Croft was brought back as a semi-regular in the final season of I LOVE LUCY, where she played the likable new Connecticut neighbor Betty Ramsey.
Once Vivian Vance decided to leave THE LUCY SHOW in 1965, Lucy knew she wouldn't be able to go it without a regular gal pal by her side. She briefly toyed the idea of bringing in either Ann Sothern or Joan Blondell, but both of them were scrapped from consideration. Lucy then reached out to Croft (who had already appeared several times on THE LUCY SHOW as Audrey) to play Lucy's new girlfriend Mary Jane Lewis (which was the actress's real name due to her marriage to producer Elliott Lewis). Croft came into THE LUCY SHOW as a regular cast member shortly after the show's mid-series shift to California. She was a good counter to Lucy as well: daffy, still attractive, but yet not quite as assertive as Vance had been. She also appeared as a regular on HERE'S LUCY as basically the same Mary Jane character.
Doris Singleton played Carolyn Appleby (originally Lillian) on I LOVE LUCY in the 1950s. She was a frenemy of Lucy Ricardo and Ethel Mertz. Perhaps the two most famous episodes involving Carolyn is the one where she loosing her glasses and Lucy forces a relationship with Van Johnson to appear popular with the Hollywood elite, and the episode where Carolyn and Lucy try to upstage one another concerning their kids' birthday parties. I don't believe Singleton ever appeared on THE LUCY SHOW, but she appeared on HERE'S LUCY two separate times. She appeared in the first episode of the latter series as Harry Carter's (Gale Gordon) secretary who Lucy replaces in the office, and later as Lucille Ball's personal secretary in an episode where Lucille Ball guest starred as "herself" to cross-promote her newest movie MAME (1974). It was one of the final HERE'S LUCY episodes filmed.
I like how Lucy tried her best to keep the same cast surrounding her. She seemed to be the most reliant on Vivian Vance and for good reasons. Vance was her gal pal on I LOVE LUCY, one of the biggest hits TV's ever seen, and Lucy knew that she and Vivian worked well together. That's why she insisted she return to be with her on THE LUCY SHOW and the reason Lucy was more than happy that she agreed to continue as a yearly guest star on her shows.
Lucy reached back for Mary Jane Croft to step-in for Vance once she decided to move on with her life. Lucy seemed to remain faithful to Croft and kept her as a regular on THE LUCY SHOW and HERE'S LUCY. Apparently Lucy's relationship with Doris Singleton wasn't quite as strong, or that's what I'm guessing. It could all boil down to that Lucy's sidekick was played by Vance and Croft so well that there was simply no space for Singleton to be fitted in. Even when Singleton did appear on Lucy's shows it was never easy for me to believe Lucy and Doris (or her characters) were really "friends". They worked better when the "rivalry" between them was played up. The comedy drawn from that was priceless.
Even so, Lucy seems to have a reputation of underappreciating her female co-stars. She seemed to hold Gale Gordon in a high regard, but felt that the women around her (with the possible exception of Vance) were interchangeable and replaceable. Even if that's how Lucy worked, I still think the women she wanted and had around her throughout her TV career were wise and good choices. Each of them did some good work on her shows and don't get the recognition they need on our forums.