I have so many shows I want to talk about for all of the suggested topics, but I saw the "favourite shows from the late 90's or early 2000's" one and had to go with that. So all of my choices are older/cancelled shows, but ones I think would be worth checking out if you love YA books. I'm going to go with shows that first aired between 1990 and 2005 (with maybe one or two exceptions).
All of the links will take you to the youtube trailers for the first season of each (be warned though, most of the trailers are very dated and pretty bad). And all of the gifs are from the shows.
1. Firefly (2002-03) note: the trailer sucks and doesn't do it justice
I figured this would be a good one to start with seeing as space sci-fi seems to be a thing in YA publishing right now thanks to Star Wars revival. It's basically like a space western revolving around a ragtag crew on a spaceship and it's so good -- it's such an awesome cast of characters. The show didn't air for very long but there's a movie (Serenity) too and it wraps up well. If you're into space-set SF, this is a good one to watch.
2. Roswell (1999-02)
If you liked Twilight or Jennifer Lynn Armentrouts Lux series, you should check this one out. It's about a teenage girl called Liz whose life gets flipped upside down when she nearly dies but is saved by one of her classmates who turns out to be an alien and it revolves around their relationship and this secret they're trying to keep but there's people who want to hunt him (and his sister & friend) down. It's exactly as cheesy as it sounds, but it's cute.
3. Instant Star (2004-08)
This one...I don't know why I have such a soft spot in my heart for this one, but I love it. It's about a girl called Jude who has just won a televised talent contest (very X Factor/American Idol), and it's about her career and relationships (friends/boyfriends/family) and fame and...it's just really cute, and the music is actually decent because Jude is played by Alexz Johnson who has an excellent voice. Also, in the later seasons, you'll see mini-Tatiana Maslany before she got all clone famous. If you're into YA books that revolve around music, try this.
4. Dawson's Creek (1998-03)
This one...if you like contemporary YA, it's a good one to watch. Especially if you like really cheesy, really sentimental stuff. It's basically about a bunch of teenagers and their lives and relationships from high school post-college. It's hard to condense 5 years of a show into a paragraph but it focuses a lot on romance and friendship and family, and it tackles story lines about mental illness and sexuality (one of the main characters is gay) and financial struggles and...yeah.
4. Dark Angel (2000-02) or Dollhouse (2009)
If you like dystopian YA (or ones like Maximum Ride), this one is excellent. It's about girl named Max (I think she's 19 at the start of the series) -- she's a genetically enhanced soldier who escaped a secret government facility when she was a child, where they were trying to make an army of perfect soldiers. It's set in Seattle after an electromagnetic pulse caused chaos in the US. The story basically focuses on her as she tries to live a normal life while trying to find the kids she escaped with and trying to stay hidden from the people that made her. It's... better than I'm making it sound. Show ends on a cliffhanger but there's two sequel novels and a prequel that wrap things up. And, like Dawson's Creek, it has younger Jensen Ackles in it being adorable.
Dollhouse works for this too but has a very different feel to it. Less gritty and more focused on technology. It's about a machine that can basically copy or erase or create peoples minds (personalities, memories, phobias, skills, talents, etc.) and this company is using it to cater to rich clients desires (e.g. a grieving widow wanting another day with their husband, someone wanting to solve the murder of their relative, government agencies needing very specific skill sets). I am not explaining well at all, but it's really good.
This one is about a teenage girl named Kim who falls for her best (female) friend, Sugar. The show basically revolves around Kim's obsession with Sugar and coming to terms with her sexuality, as well as dealing with her family issues too. I remember really liking this when it first aired, but I tried rewatching it recently and there were things that didn't even register with younger-me (like the fact that Kim very seriously considers getting Sugar drunk so she can make a move on her)...but aside from its issues, it's worth checking out. (Also, it has really young, pre-Hollywood fame Andrew Garfield)
6. Point Pleasant (2005) the only fully English trailer I could find had major spoilers, so that'll have to do
If you like supernatural/supernatural apocalypse type books, this is a good series to watch. It's about a girl who washes up on the beach of a small town and strange things start happening. Because she's the daughter of the devil. The show was cancelled after one series so it does end on a kind of cliffhanger but if you don't need a happily ever after type ending with lots of closure, it's still good.
7. Charmed (1998), Switch (2012) or Hex (2004)
If you like books about witches, try one of these shows. Charmed is a more obvious ones and I don't think I have to give much explanation for it -- three sisters discover an old spell book in their attic, magic ensues (earlier seasons have a dated feel to them).
Switch is a more fun one, it's just a regular group of friends living in London...except their witches, and there's a whole lot of spells gone awry.
Hex is slightly darker and it's set in a college and there's witches and (lesbian!) ghosts and, from what I recall, demons/angels/fallen angels. And it has Michael Fassbender which I didn't even remember until I was writing this post.
And I'm going to get really obvious with these last three...
8. Buffy the Vampire Slayer (1997)
If you like vampire books or supernatural books or girls-generally-kicking-ass books... This show. The earlier seasons are very, very 90's and parts of it didn't age well, but it's all part of the charm.
9. Gilmore Girls (2000)
I think everyone and their mother has seen this, or at least heard of it, but if you haven't watched it yet then you should. If you're into contemporary YA with romantic subplots and a strong focus on female relationships (mother/daughter in particular, but also friendships), then this one...watch this one. Binge watch it before the new season airs this year on Netflix!
10. Veronica Mars (2004)
Like GG, this one is very well known...but I'mma talk about it anyway because it deserves it. If you're into Nancy Drew type stories, the ones where teenage girls are solving crimes and outsmarting all the idiots who underestimate them, you'll love this.
Aside from the fantastic cast, really fun plot and romantic subplots that make me smile, it's one of the few examples I can think of where I really liked the way it handled a rape storyline...Veronica was changed by what happened to her, but it didn't destroy her, didn't define her and it never felt like "oh, rape is a fun plot device!" it was handled really well and it was just a thing that happened to her without it becoming her entire story (I wanted to mention that because a lot of YA books recently have been revolving around that subject too).
There were loads of other 90's-early 00's shows I loved (I was so obsessed with Sister Sister for a while and Sabrina the Teenage Witch) but these ones are less dated and definitely have YA appeal.
Have you seen any of these? Are there any you'd recommend?