One truly great season can place a show in the pantheon of TV history. Although the best titles tend to be TV shows where every season is great, not every series can meet that almost impossible standard. Besides, some of the greatest TV seasons of all time have come from shows punching above their weight for just one season, or even from series which were canceled prematurely just as they were reaching their pinnacle.

A single string of classic episodes is enough to put a small-screen project on the map, and a great may well maintain its standing in the hearts and minds of viewers even if there’s a decline in quality following its run. Whether they're TV shows with the best debut seasons ever produced, or shows that just kept getting better until their final bow, .

Seminal comedy-drama Sex and the City had already flipped the TV narrative for women in search of romance long before its last season, with its wry observations about male New Yorkers delivered from an unapologetically feminine perspective. But , as it saw Sex and the City’s main characters grow in unexpected and hugely rewarding ways.

Samantha’s battle with cancer, Charlotte grappling with infertility, Miranda’s surprise romantic reunion, and Carrie finally realizing what she’s looking for in a relationship are all highlights of this incredible outing. .

It’s no surprise that Don Draper actor Jon Hamm’s favorite Mad Men episode comes from the show’s fourth season, which is when this supremely slick drama about the rise of Madison Avenue’s advertising industry really laid down a marker for the rest of television.

Mad Men was already one of the best things on TV before 2010. However, the new layers of complexity it added to . This stands out among the rest of the series, and its ability to elevate the show overall makes it one of the greatest outings of television of all time.

Arrested Development’s first three seasons are now collectively considered to be . But season 2 just pips the others to the title of best Arrested Development season, even if seasons 1 and 3 aren’t far behind. Quite simply, season 2 contains most of Arrested Development’s best episodes, and many of the show’s funniest moments, from Tobias Fünke’s shameful admission, “I just blue myself,” to the second shark jump of Henry Winkler’s career.

After immediately hitting its stride in season 1, . As well as its powerfully emotive and hilariously cringe-worthy storylines about teenage struggles with identity and sexuality, the season showcases Sex Education’s best characters at their finest. The character arc of headmaster’s son and notorious bully Adam Groff should be singled out for special mention, as one of the most authentically moving ever depicted in a coming-of-age TV drama.

Creator, writer, and actor Phoebe Waller-Bridge ended Fleabag after just two seasons, but the unparalleled brilliance of the show’s 12 episodes make them both seasons of the highest quality. Season 1 of Fleabag, in particular, is astonishingly good, from its ridiculously funny portrayal of the title character’s pretentious step-mother and overly sensitive ex-boyfriend, to its stunning twist at the end of episode 6.

Waller-Bridge’s expert breaking of the fourth wall, honed via the stage show form in which Fleabag originated, makes . There's a reason Fleabag remains such a memorable hit, and it's because it got off to such a strong start.

The satirical black comedy in Succession makes Fleabag look like fun and games, and the show’s dark brand of humor is employed to perfection in its masterful final season. , as the time finally arrives to reveal the successor to billionaire Logan Roy’s business empire.

Succession’s ending doesn’t disappoint, as its writers rise to the challenge of both shocking and satisfying their audience — all while delivering big laughs and spine-chilling realism. It's no exaggeration to say that season 4 features some of the best installments of the entire series, particularly the surprising and shattering third episode.

Following in the footsteps of its acclaimed British counterpart, the U.S. version of The Office was always going to struggle at first. The show gradually grew into its own, however. And .

, including its two-part premiere, “Weight Loss” and “Moroccan Christmas.” Undoubtedly the highlight, however, is The Office’s funniest cold open, at the beginning of “Stress Relief." The Scranton branch’s reaction to Dwight’s office fire drill has become a legendary TV moment in the years since it first aired.

A handful of different Cheers seasons could have ended up on this list. However, with the breadth and depth of its hugely ambitious storylines.

Cheers was canceled when lead actor Ted Danson announced he was leaving the series, and its writers and producers made sure. The season features some of the show’s biggest laughs, including the loss incurred by the gang’s final St. Patrick’s Day bet, as well as most of its saddest goodbyes.

It was a landmark moment in horror TV, so . The shock and novelty of AMC’s brutally realistic and stunningly realized dystopian zombie series were never going to hit as hard after season 1. Of course, the show had to start strong if it was going to last.

Thankfully, it hooked viewers with its first season, beginning with lead actor Andrew Lincoln’s favorite episode and building a truly mesmerizing survival story from there. Perhaps The Walking Dead was never quite as good again, but that just proves what a standout season 1 was. It kicked off a groundbreaking and long-running TV franchise by delivering a gut punch from the start. It deserves a spot among TV's best seasons for that alone.

For most TV series, the loss of two leading cast members would spell big trouble. Yet when Wayne Rogers and McLean Stevenson exited the cast of M*A*S*H after three seasons, it forced the team behind the show to create two of its funniest characters and take it to the next level. Cue B.J. and Potter’s arrival to take the places of Trapper and Blake, and the greatest sitcom juggernaut of the 1970s went from strength to strength.

M*A*S*H* season 4 stood out for its ability to adjust and pivot — and maintain a high quality the entire time — but that's not all this outing of television had going for it. The season proved a turning point for M*A*S*H*, laying the groundwork for its overall success. And season 4's finale, "The Interview," delivered some of the finest writing of the series, helping to elevate this outing to one of TV's best.