From "Mad Men" to "Friday Night Lights," these 20 dramas helped define the modern TV landscape — even if they're still a part of it.

Like it or not, TV dramas often set the standard for how television eras are remembered. Be it awards attention or Top 10 lists, dramas are looked to as a guide post for where we are, where we’re headed and what’s worth revisiting from the past. Series like “The Americans” and “Mad Men” look back to break down where we are now, while iconic moments in time are captured in series “of the now” like “The Wire” and “The O.C.” Eras matter, in your life and in all our lives, and these 20 series, all premiering in the last 20 years, have defined the past two decades in every aspect imaginable.

Joss Whedon may have traded the supernatural for superheroes in recent years, but his first series remains his crowning achievement as King of the Nerds. “Buffy” was strong as a whole, with a well-rounded cast, top-notch writing, and a healthy dose of classic Whedon humor, but it’s in examining the series’ most famous episodes that the true genius shines through. Three “Buffy” episodes are widely regarded as some of the best in TV history: the eerily silent “Hush,” featuring only 14 minutes of dialogue and the scariest villains in the entire show; the genuinely catchy musical numbers of “Once More With Feeling,” which combined Buffy’s existential crisis with a musical-inducing demon; and “The Body,” a study in overwhelming grief as Buffy and her friends deal with the death of her mother. While “Buffy” may not be as critically acclaimed as other shows on this list, it redefined the supernatural genre, paving the way for countless other shows — none of which have lived up to to the original vampiric cult favorite. – Kate Halliwell

“Oz” (1997-2003)

Given how much attention is given to early HBO dramas “The Sopranos” and “The Wire,” it’s almost criminal just how overlooked “Oz” has become. Critics adore it, but you’ll be hard-pressed to find any “Game Of Thrones” or “Breaking Bad” fans who have seen a single episode. Ironically, “Oz” paved the way for nearly every Golden Age TV drama in its path. So much of what we’ve come to expect from TV drama — antiheroes, brutal violence, moral ambiguities, the fearless disposal of main characters — was born at the Oswald State Correctional Facility, where racial, sexual, and economic conflicts within the prison system gave way to some of the most complex characters TV has ever seen. Each episode, co-written by creator Tom Fontana, dynamically weaves a single theme through both the present storyline and flashbacks revealing inmates’ unspeakable crimes, all narrated by Harold Perrineau Jr.’s Augustus Hill with a lyrical slam pulse. “Orange Is The New Black” has used this format in recent years to create its own memorable world, but it could only dream of hitting as viscerally as “Oz.” At times brutally grounded and surreally poetic, the show uses its fictional environment as a microcosm for our society at large, showing how the divides and conflicts manifested in prison first start in the neighborhoods we live in. “Oz” has a burdensome power that you have to reckon with. – Zack Shark

“Queer as Folk” (UK) (1999-2000)

With this intimate look at gay life in Manchester, England, creator Russell T. Davies brought joy, wit and pathos to the stories of Stuart (Aiden Gillen), Vince (Craig Kelly) and Nathan (Charlie Hunnam) as they struggled to find love in the city’s vibrant club scene. Balancing “Doctor Who” references with surprisingly explicit love scenes (yeah, look at that cast list again — some of the show’s hottest sex features “Game of Thrones'” Littlefinger and baby Jax Teller from “Sons of Anarchy”), the original “Queer as Folk” was groundbreaking for British television and even game-changing for the U.S., when Showtime created an American adaptation that ran from 2000-2005. While short-lived in comparison to the remake, the original version remains singular and iconic. – Liz Shannon Miller

Here’s the pitch: A young, close knit group of Presidential staffers fight the good fight, with episodes centering around wonky debates over sexy topics like the census, foreign aid, and nuclear energy. Hard to believe, but it was a formula that that led Aaron Sorkin’s NBC drama to capture an audience of over 20 million weekly viewers and four consecutive Emmys for Outstanding Drama Series. Mixing the hard realities of modern politics and Sorkin’s romantic belief that a dedicated group of passionate people can bring about positive change, the show was equal parts entertaining and educational. Predictably, the show teetered after its fourth season, when Sorkin and his playful dialogue moved on, but under the leadership of showrunner John Wells the “West Wing” successfully reinvented itself with longer, more sober story arcs centered around characters’ existential/career crises and an oddly prescient election to replace President Jed Bartlet (Martin Sheen), which predicted so many real-life political stories, including the 2008 match-up between Senators Obama and McCain. – Chris O’Falt

READ MORE: ‘The West Wing’ Reunion: Aaron Sorkin and Cast Remember How the Internet Saved the Series

“The Sopranos” (1999-2007)

The greatness of “The Sopranos” cannot be overstated. Its lavish praise will never be hyperbolic. HBO, for all its excellent offerings, will never do anything better. David Chase’s six-season mob drama is equal parts American opus and Shakespearean drama, one that encompasses the grand spectrum of human emotion and experience (especially as it applies to strip club-loving tough guys) through the tight lens of what could be a slightly alienating focus. Mobsters have long entertained American audiences, but to distill the crime drama down to a series that is just as concerned with domestic troubles as it is with Mafia-related violence is bold indeed. Or, in other words: It’s just really, really good (and super entertaining). “The Sopranos” never shied away from its roots as a show about the mob, but it also fully embraced the kind suburban ennui that made Tony Soprano — a larger than life character — feel oddly relatable and often even kind of lovable. While Chase’s series is hardly in danger of being forgotten or maligned, its divisive final shot is often the subject of close reads that forget to acknowledge the kind of subtlety and power that ran through the entire series. It’s not just Tony’s last meal (maybe) that deserves a deep dive. It’s the entire series. – Kate Erbland

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