5. Season 1
The one that started it all. Season 1 holds up surprisingly well in comparison to the first season of other long-running dramas, and it’s mostly because the show knows to focus on the chemistry of its actors from the start. Everybody brings it, and now, over a decade has passed, and there’s a joy in seeing characters like Severide and Casey so much younger.
Season 1 has some clunky moments, and does more hand-holding than its predecessors, but it makes sense since we’re all still getting to know the characters. This is the season we were most pleasantly surprised by on rewatch!