Dr. Eleanor O’Hara is one of the most compelling characters in Nurse Jackie, serving as a sharp-witted, glamorous, and deeply loyal best friend to Jackie Peyton. She is a British emergency room doctor who brings both sophistication and biting humor to the series. While she exudes confidence and effortless charm, Eleanor is not without flaws—she struggles with commitment, emotional intimacy, and, eventually, the realization that she has enabled Jackie’s self-destructive behavior for far too long.