The Simpsons, which is the longest-running American animated series, has made us laugh, cry, and feel love for the last three decades. It saw Baby Boomers laughing at hidden jokes their Millennial kids couldn't understand at the time, and it saw those same Millennials showing The Simpsons to their own kids - a staple animated series any generation can find relatable and loveable.

Crime drama television series could never get old or boring for the audiences, and Law & Order: Special Victims Unit proves it with its 23 seasons and 506 episodes! The lives of detectives and agents, however, aren't romanticized here, and the series' creators do not shy away from the grim reality of the job. That is probably one factor that makes this series so appealing, too. The crimes, heinous and unbelievable, are often loosely based on crimes that truly happened, making it all into an even more thrilling watch. Creating such a long-lasting series is basically a science; how else could you explain its undying popularity?

Gunsmoke, a television series of enviable longevity, is the second Western series written for adults, as The Life And Legend Of Wyatt Earp beat it to the title just by four days. Gunsmoke is the epitome of the Wild West, an epic legend of America's youth. It's Oregon Trail, gunslinging cowboys and damsels in distress; it's never-ending adventures and misfortunes of the settlers. A glimpse into the past enacted by a talented cast and written by ingenious scriptwriters, Gunsmoke proudly holds its title as one of the longest-running television series ever - twenty years and 635 total episodes!

Lassie, the legendary Rough Collie, has had plenty of incarnations both on TV screens and in cinemas. However, the longest-lasting stint started in 1954 and ended in 1973 - seventeen seasons of Lassie's adventures portrayed by six different superstar dogs! You know the story - Lassie is the smartest dog on Earth, living on a farm and helping her humans with various tasks, troubles, and just generally having fun. However, one of the seasons of this show was dedicated to Lassie's solo travels in the wilderness, making it one of the rare series having no human leads! And if you're up for some good old naive fun, we are sure you can find the original series lurking somewhere around on the internet.

The original Law & Order series began its run in 1990 and ended it after twenty solid years. However, both the creators and the fans still saw its potential, and that wasn't really the end for this police procedural and legal drama set in New York City, as it got a new spin-off show just a year later. Anyway, each of the original series’ episodes was usually segmented into two pieces corresponding with the name Law & Order. Roughly half was always dedicated to the police and detective work (Law), with the second half showing courtroom proceedings, and ultimately justice (Order). And, since we all know that true (or fictional) crime never gets boring, the series' success isn't so truly unbelievable, right?

Followed by controversies for its offensive themes, dark humor, and violence, Family Guy nevertheless has gained a cult-like following throughout its running years. There's probably no need to introduce you to Peter, Brian, Lois, and the gang any further, as the animated series isn't the only place where they appear. You might've also met the Griffin family in books (yup, there are several of those based on the Family Guy series), live performances, video games, or even their official merchandise. Despite the controversies, Family Guy is a well-written animated sitcom that bravely talks about pressing social issues, employing an unusual sense of humor and unexpected spoofs that come to life by a very talented voice-over cast. Oh, and what's interesting about the show is that even in the time of computer-generated everything, the series is still drawn by hand, and it takes about ten months to complete just one episode.

The series Bonanza (prosperity in Spanish) sure did prosper for a very long time - fourteen years, fourteen seasons, and 431 episodes in total! The series is set in the 1860s and centers around the life of the wealthy Cartwright family of Virginia City, Nevada. Besides giving us an awesome glimpse into the past of the Wild West, Bonanza is also known for presenting serious moral dilemmas, of which the viewers couldn't (and still can't!) get enough.

NCIS: Los Angeles is the second series in the NCIS franchise and a direct spin-off of the original show. Without its predecessor's success, we wouldn't have seen this thrilling continuation of a military drama and police procedural series, starring LL Cool J, Chris O'Donnell, and Daniela Ruah. Here the exploits of the Los Angeles-based Office of Special Projects are as cool as ever since its agents are most likely to go undercover to infiltrate the criminal element's workings. NCIS: Los Angeles ran for an honorable thirteen seasons and 288 episodes, full of sunshine, palms, and heinous crimes. All the stuff we like!

1962's The Adventures Of Ozzie And Harriet starred the real-life Nelson family. Where else can you find that? The Nelsons consisted of Ozzie and Harriet, a popular entertainment duo of the time, and their two sons, David and Ricky. The idea behind the series is ingeniously simple, yet one that we can all relate to - it's the Nelsons living their life and dealing with your regular everyday problems. Nothing can beat that in relatability, really! Interestingly, when Ozzie and Harriet's kids grew up and married, their actual wives got written into the script and also appeared in the show. At one time, The Adventures of Ozzie and Harriet was known as the longest-running live-action sitcom series until It's Always Sunny In Philadephia surpassed it in 2021 with the release of its fifteenth season.

My Three Sons, a series with an honorable twelve-year run, proves once again that the idea behind a great show doesn't necessarily have to be a very complex one. In fact, it most likely has to be something that the majority of the audience finds closely relatable, and My Three Sons, with its depiction of a widower, Steven Douglas, raising his kids, hit the jackpot. And the viewers get to enjoy their daily lives, hardships of raising kids, and being a single parent for a total of twelve seasons and 380 episodes that never got lesser than they first were.

Grey's Anatomy, a medical drama, started its run in 2005 and, after eighteen seasons, still hasn't lost its wind! Yep, for eighteen seasons and a new one confirmed for this year, we got to follow interns, residents, and attendants as they developed into seasoned pros. You might've heard that working in the medical field is very demanding, and once you see these young doctors trying to balance their personal and professional lives, you'll see that those talks aren't lying at all. Since its inception, the series has been christened a 'phenomenon' by critics due to its longevity and unwavering position at the top of the ratings.

Criminal Minds, one more police procedural crime drama on our list, has had an honorable run of fifteen seasons and 344 episodes in total. However, what sets this series apart from all the rest of the criminal ones is its unique premise for the time. Here, the story centers around a group of criminal profilers working for the FBI. And once you see those three letters, you know that thrills are to be expected! So, the group, using behavioral analysis and profiles, helps solve crimes where the perpetrators are listed as Unknown Subjects. Sounds a bit similar to the more recent hit series, The Mindhunter, doesn't it? So, if you like to find yourself immersed in the world of FBI agents, give this series a try; its longevity, after all, isn't circumstantial.

Dallas is the epitome of a prime-time soap opera, having lasted for thirteen years, fourteen seasons, and 357 episodes. It's a story as old as the world itself - two feuding families united by marriage have to somehow co-exist in one place. You bet that there are dirty schemes, lies, and envy mixed in with love, heartwarming moments, and the highs of life. A tight plot and a talented cast secured Dallas its longevity, and you wouldn't believe how good and immersive the series actually is.

CSI: Crime Scene Investigation is the original series in the CSI franchise that ran for an enviable fifteen seasons and 337 episodes. Now, we all know that not everything shown in this procedural forensics crime drama series is part of an actual detective's job, but don't kid yourself here; you did want to be a detective after watching this series. I know I did! It's truly unbelievable how this series managed to hook audiences depicting detectives solving crimes by using physical evidence and how much drama and thrills it generated. No wonder, though, that because of the original series’ success, the CSI franchise added in quite a few spin-offs afterward.

Supernatural, a dark fantasy series, follows two brothers on their hunts for demons, ghosts, monsters, malicious entities, and such. The brothers, Sam and Dean, run their demon-hunting stint as a non-profit, and to pay for living and the equipment needed for their activities, they often turn to various law-breaking means, such as credit card fraud, to fund their escapades. The combination of their supernatural shenanigans, a plot that delivers one twist after the other, and a talented cast secured this series an enviable run of fifteen seasons and 327 episodes of pure entertainment.

Knots Landing, a spin-off of the Dallas series we talked about earlier, transfers the action from the world of rich oil tycoons to the suburbs of Los Angeles. Knots Landing follows the lives of four married couples, and the span of topics it touched in its fourteen-year run varied from marital strife to murder and from drug smuggling to politics. Now, when the series is as ripe with interesting topics as this, it is no wonder that the audience's interest didn't wane for such a respectably long time.

American Dad!, an animated series delivered to us by the same Seth MacFarlane of Family Guy fame, follows the lives of the Smith family. Stan is a CIA agent, Francine is a housewife, their daughter Hayley is a ferocious leftist, and Steve is their dorky high schooler son. Besides this normal-sounding family, they, uhm, 'own' a goldfish that has the brain of an East German athlete and an alien called Roger. Unlike MacFarlane's other series, American Dad! mostly leans on the quirky family members for comedic situations, and you won't find that many setup-punchline jokes here. So, basically, it's just a pretty 'normal' life of a pretty 'normal' family. By now, American Dad! has a proud number of nineteen seasons under its belt, but two more seasons are already confirmed. Will this series beat the longevity of The Simpsons? Only time will tell!

ER, a medical drama series created by novelist and physician Michael Crichton, followed the inner life of emergency room workers for a solid fifteen years, fifteen seasons, and 331 episodes. The critical situations faced by the staff kept the viewers on the edge of their seats, and as much as you might think medical employment to be dull, the series will definitely prove you wrong. Because of that and its talented cast, tight plot, and truthful depiction of this work, ER won 115 awards throughout its run, including the prized Peabody Award.

The Danny Thomas Show, a sitcom starring Danny Thomas himself, who was an iconic entertainment figure at the time, lasted for eleven years, eleven seasons, and 343 episodes in total. Here, Thomas played the role of a successful comedian and entertainer (which he was in real life), managing a family life for which he had virtually no time. Besides plenty of hilarious comedic situations, gags, and relatable family matters, The Danny Thomas Show's wildcard for attracting audiences was its guest stars. Everybody famous at the time appeared in this show, so you could've expected to see the likes of Zsa Zsa Gabor and Lucille Ball in the show!

Beverly Hills, 90210, a teen drama created by Darren Star, ran for ten seasons, 293 episodes and found its popularity worldwide. The story starts with an introduction to the Walsh family, who just moved from Minneapolis to Beverly Hills. If that isn't exciting enough, just wait until their kids, Brandon and Brenda, begin attending the local high school. Now, the Beverly Hills teens are almost the same as anywhere else, just a bit more flamboyant and edgy. So trust us when we say that there are loads of drama, misadventures, lies, and schemes in Beverly Hills, 90210 - exactly the stuff that never goes out of fashion!