What were the names of the Ricardos' landlords and best friends?

What were the names of the Ricardos' landlords and best friends? They were Fred and Ethel Mertz. The married couple lived in the same New York City brownstone as Lucy and Ricky Ricardo and became the Ricardos' closest friends and frequent comic partners.

Fred Mertz was played by William Frawley, while Ethel Mertz was played by Vivian Vance. In the show's backstory, Fred and Ethel had once worked in vaudeville before buying the apartment building. Their experience in show business also made them natural participants in Lucy's schemes and Ricky's performances.

The relationship was more than a landlord-and-tenant arrangement. Lucy and Ethel regularly plotted together, while Fred and Ricky often teamed up to counter their wives' plans. Viewers sometimes remember the names as a single comic catchphrase, but Fred and Ethel are separate characters: Fred is the husband and landlord, and Ethel is his wife and landlady.