Soon enough, we're going to be watching spin-offs of The Vampire Diaries and Once Upon a Time, proving that too much of a good thing is never enough. Spin-offs often seem like pointless cash grabs — but there have been some fantastic exceptions. Here are 10 science fiction and fantasy spin-offs that actually rule.

10. Stargate Atlantis

After 10 seasons of Stargate SG-1, you might think that whole new Stargate series, with some characters crossing over, might be unnecessary — but Stargate Atlantis is fun as heck and series regulars like Rodney McKay, Ronon Dex and John Sheppard became as much audience favorites as ever Jack O'Neill and Daniel Jackson were. And the later spin-off, Stargate Universe, also had its moments, especially right before they pulled the plug.

9. She-Ra: Princess of Power

Everybody loves He-Man and the Masters of the Universe — but He-Man's pal had a glorious career all her own. She-Ra was created in the early 1980s when Mattel tasked rising executive Jill Elikann Barad with creating an action figure to appeal to girls — and eventually, She-Ra was having amazing adventures all her own, including cheering up Sorrowful the Cowardly Dragon and saving the unicorns on Unicorn Island from being enslaved by Hordak.

8. Ashes to Ashes

The original U.K. Life on Mars was just two seasons of concentrated awesome about a present-day cop who gets knocked on the head and finds himself trapped in 1973, culminating in a brilliant ending. The spin-off, about another cop who gets shot and finds herself in the early 1980s, had some rocky moments — but the subplot about Gene Hunt belonging to a secret society was golden, and this show actually managed to carve out its own identity and address gender politics in a way Mars couldn't.

7. Torchwood

Since it returned to British television in 2005, Doctor Who has been a juggernaut, a show that many people want to imitate — but the Doctor Who magic is really hard to duplicate. So it's actually a pretty impressive feat that Torchwood took over a corner of the Doctor Who universe, and yet carved out its own identity. Torchwood's four seasons ranged from astonishingly great to face-clawingly awful — but it was always unmistakably its own animal. (The other major Who spin-off, The Sarah Jane Adventures, was reliably delightful but arguably never achieved as much separation from Doctor Who.)

6. Mork and Mindy

When you talk about spin-offs that carved out their own identity and became mighty shows in their own right, Mork and Mindy has to be the poster child. Mork from Ork originally appeared on Happy Days, the 1950s comedy about teenagers hanging out with a creepy older leather daddy. But Mork gained an identity all his own, coming back to Earth to hang out with Mindy, a young Earth woman with epic hair, and her curmudgeonly older friends. The first season of this show was both terrific and a huge hit, until the network found a bunch of ways to ruin it.

5. Angel

For the first couple seasons that Angel was on the air, the Buffy the Vampire Slayer spinoff still felt somewhat tethered to its parent show — but when Buffy left to go to a different network, Angel started to breathe on its own. The characters got sharper, the storylines more thrilling — and by the time Angel got somewhat reintegrated with Buffy, with the addition of James Marsters to the cast, the vampire with a soul already felt like he had a world all his own.

4. Batman Beyond

To some extent, every show in the DC Animated Universe was a spin-off of Batman: The Animated Series, including the Justice League shows. But Batman Beyond was a direct spin-off of Batman: TAS, in which an elderly Bruce Wayne trains his replacement, who wears a futuristic cybersuit instead of a regular Batsuit. And Batman Beyond also had its own spin-off, The Zeta Project. Not to mention, Batman Beyond was a brilliant show that took the Bat-legacy in an amazing direction. We're still waiting for our Batman Beyond movie.

3. Avatar: The Legend of Korra

What's the difference between a sequel and a spin-off? It's sort of a tricky question. But Legend of Korra is basically a new show set in the same universe as The Last Airbender where the new avatar, Korra, learns airbending from Tenzin, the child of Aang and Katara. And not only is Legend of Korra a fantastic show in its own right, it's also a very different take on the world we saw in Airbender — one which combines technology and fantasy elements.

2. Xena Warrior Princess

Xena was originally featured in a three-episode arc on Hercules: The Legendary Journeys, and she was planned to die in the third episode, "Unchained Heart." But instead, the producers decided they liked her so much, they wanted to give Xena her own TV show. In which she travels around atoning for her past crimes as a warlord and having tons of romantic tension with her companion Gabrielle. Not to mention the musical-comedy outings.

1. Star Trek: Deep Space Nine

Arguably, Star Trek: The Next Generation is a spin-off too, but TNG is a spin-off of a show that had been off the air for decades, and it rebooted Star Trek as a television venture. Deep Space Nine is more of a classic spin-off, since its pilot episode features Patrick Stewart to establish strong links with TNG, and TNG's recurring character Colm Meaney came over to Deep Space Nine as a new regular castmember. And TNG was still on the air when DS9 started. In any case, Deep Space Nine quickly established its own unique spin on the Star Trek universe, becoming many people's favorite Trek with a darker, more challenging approach to the Federation.