What was the name of Lucy's best friend in "I Love Lucy"?

Lucy and Ethel were the first of television's best girlfriends, making audiences laugh long after "I Love Lucy" left the airwaves. In real life, it was a friendship that lasted decades, and what you saw on-screen often echoed what was happening off-screen. Lucille Ball and Vivian Vance met when their legendary sitcom began, and a lifelong friendship was born. In 1951, Ball and Arnaz began looking for performers to play their two best friends, a couple named Fred and Ethel Mertz who owned the Manhattan building where Lucy and Ricky Ricardo lived in. That's when Ball met Vivian Vance, a former theater actor who had appeared in a few movies without yet finding her fortune and fame (via The Famous People). Ball recalled in her autobiography, "Love, Lucy," how she and Vance felt like friends almost immediately.

Source: The List