Shelley Winters (Shelley) had an uncredited role in the 1946 Lucille Ball film "Two Smart People" and played a version of herself in "Lucy and Miss Shelley Winters" (S1;E4) on "Here's Lucy" in 1968.
Bill Saluga (Johnson) and Lucille Ball (Cleaning Lady) had appeared together on "The Tonight Show" in 1974.
Cher's mother, Georgia Holt, played a fashion model on "I Love Lucy" in the 1956 episode "Lucy Wants a Paris Gown." She also appeared as a fur model on "The Lucy Show" episode "Lucy and Pat Collins" in 1966.
Lucille Ball is a character in the new musical about Cher's life called "The Cher Show" - at least in the Chicago pre-Broadway try-out. Cher seeks advice from Lucy when wondering whether to leave Sonny, feeling America might disapprove. Lucy faced a similar quandary when divorcing Desi Arnaz. The story of their meeting is based on tabloid magazine reports and may be apocryphal.