Sith tattoos

Hi. I'm building an original Sith character, and I want to decorate the costume with some Sith tattoo inspired markings. Does anybody have a resource for the origins, meanings, significance, etc, of the Sith Tattoos? I'm curious if they're representative of anything, personal to the wear or to the order, what other meanings they might hold. I've read the Wookieepedia on Darth Krayt, but I imagine there is some old EU lore about the tattoos that Wookieepedia didn't cover. Any insight would be great! Thanks!

You could also look for the Mortis episodes of the Clone Wars series and look for the dark side designs. It is no exactly Sith, but it’s of the last attempts of George Lucas on origins of the force, the dark side and the light. And currently the story group has been leaning towards those concepts.

That’s a great suggestion, thanks! It’s been a while since I’ve watched those episodes, but I remember them having a lot of interesting visuals. And I can definitely see the similarities between the pictures you’ve posted and some more recent characters, like the inquisitors.

I guess I have to re-watch Clone Wars now. I love it when I get to watch Star Wars in the name of research

As a nitpicky neckbearded fanboy, I feel the urge to point this out.
A lot of the EU Sith tattoo stuff originated from Maul and his body tattoos, especially the Sith in the Legacy comic.
It's known now that the markings on Maul are natural and not Sith in origin. Maul, Savage, Ahsoka, etc. are described as being like poisonous tree frogs with distinctive natural markings. They've said some of the markings may have been touched up with tattoos to make them look cleaner or more angular, but they're mostly natural.

So I think for the most part investigating the meaning of tattoos may be a bit of a dead end. But you can research Dark Side symbology and get some good ideas there.
A place I like to look is the behind the scenes guides on starwars.com for various episodes of the Clone Wars and Rebels. Usually ones where they go to temples or places strong in the force. There are examples of ancient Sith and Jedi writing and logos there.

I always thought that Maul, Savage, and Ventress’s markings were naturally occurring. I was surprised to see Maul included in the Wookieepedia under Sith tattoos! But apparently tattooing was a thing for the followers of Darth Krayt and the One Sith? This is, honestly, a part of Star Wars I’ve never gotten that deep into, so everything I know at this point came from a quick Wookieepedia read. I’ll definitely take a closer look at the dark side episodes of Clone Wars and Rebels. Thanks!

Sith tattoos are a bit all over the place. Maul was said to have Sith Tattoos done by Sidious, but then the Clone War episodes showed Savage Opress and the rest of the Night Brothers already marked. The species (Zabrak) was tattooed as a right of passage or coming of age.

In the books, sith tattoos were done to many of the new sith in the age after the Yuuzhan Vong war (Darth Krayt time frame with Cade Skywalker).