A vampire once got pregnant with their own sire. As in, the sire was the fetus.
The Tzimisce clan are fleshcrafters, meaning they can shape flesh like clay. The farther back you trace their lineage, as with all vampires, the more powerful they get and the more capable they are of doing crazy shit with it -- weak vampires can only shape flesh, but more powerful ones can shape bone, and even more powerful ones can fiddle with the nervous system. Their progenitor, the Eldest (as in "The Eldest of Tzimisce"), is the most powerful of all; the progenitors (also known as Antediluvians) are so powerful they're basically akin to demigods, with vampires growing less powerful the farther descended they are from these progenitors.
After meeting a demise of some sort, the Eldest, who's part of a generation of vampires who are so powerful they're basically gods, basically respawned himself in his favourite childe. Bonus fun fact: it's mpreg. The Dracon carried the Eldest until the Eldest recovered and rebuilt himself enough to emerge in the form of a baby. The Eldest Came Back Wrong from this, and was basically corrupted either by his demise or from his rebirth and was never the same again.
Zombie vampires are real.
They're called the Samedi. Their clan bane is to rot away each night, only to become perfectly restored during the day. After a magical ritual called the Family Reunion, they were combined with other clans associated with death (including the Giovanni) into one big clan called the Hecata.
A great civilisation was destroyed due to gay love triangle drama.
Remember that guy who got pregnant with his own sire? Yeah, he comes back here. It involves him, a Toreador who thought he was Archangel Michael, and another dude who was totally sick of their shit but kept coming back for Michael's dick. Michael cheated on his long term partner with the pregnant guy (who was not pregnant at the time, to be fair). Given that they'd been together for centuries, the cuckolded dude wasn't about to just tell him to go fuck himself, and Michael got off on making the two guys fight over him for centuries.
The great civilisation? Constantinople. It was the most powerful city in the world and was ruled by Michael, and his two boyfriends who hated each other. Eventually Michael got sick of his first boyfriend and got the pregnant guy to help him kill him, at which point the pregnant guy suddenly grew a conscience and realised he'd been in love with the dude all along (who remembers blackrom???) and got into a deep depression, which made Michael sad because he was no longer the centre of attention all the time and resulted in the decline and eventual fall of Constantinople.
One of the most powerful vampires in the world is a giant worm. Who got bombed.
So a really powerful dude called Tremere, who'd become the progenitor of the -- you'll never guess -- Tremere clan ate a powerful vampire to absorb his powers. Saulot's soul survived consumption, which meant that his soul and Tremere's battled for dominance of Tremere's body. They ended up in a stalemate that lasted over a thousand years. As part of this battle, Tremere's body inexplicably became... a giant worm? for some reason. yeah. The Tremere kept Tremere in a building in Vienna, which got bombed by vampire hunters in 2008 because even they knew not to fuck around with these guys.
It's also canon that the Tremere blood bind their clan to worm!Tremere, which involves drinking Tremere's blood. This has led to speculation as to whether or not the Tremere stuck a tap on their progenitor for ease of access.
A famous Christian vampire wanted to vore god.
This involves yet another clan progenitor. You've met the Eldest, you've met Tremere and Saulot -- this one is Cappadocius, the progenitor of the original clan of the dead, the Cappadocians.
The Cappadocians are now extinct, but Cappadocius himself was notable for being a Christian, for some reason. (Then again, so was Michael.)
Remember how earlier up I mentioned that the farther you trace your vampire lineage, the more powerful vampires get? The progenitors of the clan are third generation from Caine (yeah, the dude from the Bible, plus an E), and Caine is so powerful he's basically a god in his own right. After murdering Abel, Caine was cursed to walk the earth for eternity and never see the sun again, and turned into the first vampire.
Cappadocius's theory was that God, himself, was a vampire. Given that vampires can become more powerful by eating other vampires (see Tremere and Saulot), he wanted to become the most powerful vampire of all by tracking down and eating God. Somehow. Anyway he eventually grew bored of this and let a Giovanni eat him and wipe out almost his entire clan in a genocide for... Reasons, idk.
There's an entire clan based on the Mafia.
The Giovanni. Cappadocius allowed some random Italian dudes into the Cappadocian clan. One guy ate him, and the rest promptly set about to genociding the rest of the Cappadocian clan and taking over as the Clan of Death. They're Italian mobsters, but vampires. Eventually they'd get scared of their enemies enough to reach out to other clans associated with death, such as the aforementioned Samedi and the few survivors of the Cappadocians, to create the Hecata.
It's entirely possible that God was the first vampire.
See what I said earlier about Cappadocius voring God. It's entirely possible because Caine is godlike himself... so if Caine was actually turned into a vampire the old fashioned way, instead of via a magical spell from a being that wasn't a vampire, it makes total sense that the vampire that created him would have powers indistinguishable from actual godhood.
There's a magic ritual where someone punches your face to steal it.
Magical rituals are mostly associated with the Hecata, Tremere, Giovanni and the Cappadocians, but for some reason the Brujah (the punk clan. Yes, there's a punk clan) have this random one where they say "nice face, I'll take it", punch you in the face, and then they're wearing your face. I have no idea where they got it or how they developed it, considering they're a brawling clan, not a magical clan. Might be Early Installment Weirdness IDK.
Werewolves are descended from a powerful vampire associated with wolves
This is the fake one. The progenitor of the Gangrel clan (associated with animals, particularly wolves), Ennoia, is theorised to be Gaia, who created the werewolves, but it's just a theory. Also werewolves hate vampires so this would really piss them off. But werewolves aren't vampires, they can walk around in the day time and shit.
A torturer threw their own penis at someone in an act of protest.
Sascha Vykos, the most infamous torturer in the world (they'd later end up pregnant with the pregnant guy for like eight hundred years... it's a long story), went to a meeting with some powerful vampires during the First Inquisition, where the humans went all Salem Witch Trials on vampires and drove vampirekind into hiding. The elder vampires used their progeny as bait and pawns to fight back, which pissed off the younger vampires, which triggered a rebellion. Sascha Vykos, despite being an elder in their own right (though still very young compared to most elders), was one of the figureheads of this rebellion.
Vykos is Tzimisce. Remember how earlier on I said that Tzimisce can shape flesh like clay? Well, Vykos got so mad during these talks that they basically snipped off their penis with finger scissors and hurled it at the face of one of the elders.
The vampire who ended up coming up with the idea of vampires going into hiding to escape the Inquisition scooped the penis up and put it in a frame. Given that he was part of the artsy clan, the Toreador, nobody was surprised by this.
Fandom has dubbed it "the Great Meat Yeet."