Although no major character deaths occurred during ER seasons 1 and 2, the show did not allow its audience to get too comfortable.

Fast-forward to season 6, and there was a different reason behind a certain cast member's exit from ER. In reality, actress Kellie Martin wanted to leave the show

By the time season 8 had arrived in 2002, ER had reached new dramatic heights. This season had an event that NBC planned on purpose

Established as playing the jerk of the show, Paul McCrane portrayed the much-maligned Robert "Rocket" Romano for seven seasons on ER.

In the beginning of season 8, ER introduced a special character that would stay on the show for a solid five years.

Reaching the final year of ER's long television run, the show's last season started with a bang right out of the gate.

Considering the number of deaths featured week-to-week on the NBC series, this cast of unforgettable doctors is especially memorable.

In fact, the medical drama saw several doctors meet their demise over the decades, much to the audience's dismay.