Chicago Fire first hit the screen in 2012, and soon became one of television’s most beloved shows. In its 11 seasons, the show has introduced audiences to plenty of complex, endearing, and heroic firefighters and paramedics.

Plenty of those people have come and gone — including fan-favorite characters — so it can be hard to remember who the original Firehouse 51 crew was composed of.

The son of Boden’s old friend, Benny Severide (Treat Williams), Kelly Severide was a key player throughout all of Chicago Fire up until his mid-season departure in Season 11. In that season finale, Severide’s wife, Stella Kidd (Miranda Rae Mayo) decided to track him down and bring him back to Chicago, so he may or may not return to his crucial role in 51 for Season 12.

When audiences first met Severide, he was battling intense pain that he feared would keep him away from his job. His best friend and confidant, Shay, was helping him get medication under the table, which caused some hiccups for the pair in the first season.

Jesse Spencer as Matthew Casey
Seasons 1-10
Much like Severide, Casey is one of the people who shaped Firehouse 51. Throughout his time on Chicago Fire, he proved himself to be a valuable leader, good friend, and loyal partner.

Casey’s long-lasting relationship with Dawson — and their potential co-parenting of their foster son, Louie — was a focal point of his earlier seasons on the show.

He went on to date Sylvie Brett (Kara Killmer), but ultimately had to leave her and Chicago behind to move to the west coast and care for the children of his late coworker, Andy Darden, in Season 10, Episode 5 (“Two Hundred”).

Luckily for fans of Casey, he’s reappeared throughout the last two seasons, visiting Chicago and his old 51 family regularly.

Monica Raymund as Gabby Dawson
Seasons 1-8
Casey’s long-term partner, Gabby Dawson, was a force to be reckoned with during her time at 51. She began as a paramedic, and it was immediately clear that she was willing to put her life on the line for her patients.

As time went on, Dawson decided to pursue her goal of being a firefighter, where her bravery shined even brighter. She ultimately left the show in Season 6, Episode 23 (“The Grand Gesture”) so that she could be an emergency responder in Puerto Rico.

Like Casey, she returned back to the firehouse after her big goodbye, making a few appearances in Season 7. She also appeared in a video that Otis and Cruz found during Season 8, Episode 9 (“Best Friend Magic”).