I know about Cronvangr Cave, Moldering Ruins, Bloodlet Throne, Morvalt's Lair, and of course Harkon's castle

Are there any other locations anyone knows about?

I'm in need of vampire dust for alchemy.

I can't remember the exact name but think it's called Broken Tooth Cave and it's east or southeast of Rorikstead just off the road.

OH! And Mara's Eye Pond maybe halfway between Whiterun and Windhelm.

Haemar's Shame I think it's called, the one Barbas takes you to.

And Redwater Den.

There's also that one cave in the northwest corner of the map, right across from Volskygg's entrance. Pinemoon Cave, I think it's called? The Solitude court wizard sends you there to clear it out.

Excellent. Thanks for the replies!

There is some kind (depending on your level) of master vampire at the end of Shriekwind Bastion also.

I forgot about there, similarly, there's at least one or two (I think) in the Solitude catacombs during the Potema quest.

Reason I need that dust because I need it for Regenerate Health potions. Finding those more efficient than jugging Ultimate Health potions. Also trying out a Regenerate Health build.