While the 15-season run of ER definitely helped launch the careers of future stars, it also became a magnet that attracted some of Hollywood's greatest legends and award-winning heavyweights. That's what happens when you're one of the greatest medical shows to ever grace television. Some drop in for a punchy single-episode cameo, while others stuck around for a multi-episode arc.

From silver-screen icons to Oscar-winners, these guest performers often provided a different kind of electricity—rooted in their lived-in gravitas, star power, and the thrill of seeing a familiar face stroll (or wheel) through the halls of County Gen. If anything, it remined fans that in Chicago's busiest emergency room, prestige and chaos often go well when hand in hand.

10 Bob Newhart

Image via NBC

See Full Page