official Soundtrack
Alternia
ColoUrs and Mayhem: Universe A&B
I know this isn't actually a karkat theme, but it's related to him.
Vol 7-8
Unused
hover to see title
Fanworks
I am NOT including Broadway Karkat. We all know it exists.
Tomb of the Ancestors
Once again, I know it is isn't a KARKAT theme
PhemieC
The Homestuck Fan Musicians