Holy cow, “ER” has been on a long time! “ER” celebrates its 300th episode tonight with the aptly titled “300 Patients,” guest-starring Peter Fonda. This is ER’s 14th season.

“ER” made its debut on September 19, 1994 and launched the career of a handsome guy by the name of George Clooney (among other famous faces who have graced the series). ER can also brag about gaining the most Emmy nominations of any series, with 120 so far, as well as being the longest running medical drama.