He stated that he left because he wanted to spend more time with his family and friends and to make room for the upcoming generation. However, in 2009, Wyle returned to ER during its fifteenth and final season for five episodes, including the series finale.

What happened to Noah Wyle on ER?

Wyle played Dr. John Carter, starring in 254 episodes throughout the show's 15 seasons, which is the most of any actor on ER. ... Behind the camera, Wyle has been a producer — working on Falling Skies, Shot, The Librarians and A Killer Story — and a director. He also wrote two episodes of The Librarians in 2016 and 2017.

Why did Noah Wyle break from ER?

Noah Wyle says ER exit was "horrible" and admits he "hated" one of his co-stars. ... Wyle explained that the birth of his first child Owen in November 2002 led him to leave the show, although he would later return for a handful of episodes in the final season.