In the DC Universe, Ultraman's origin story typically involves him being from a parallel Earth. He gains his powers through some sort of scientific or otherworldly event. He often has abilities similar to Superman but with a darker twist, using his powers for more self - serving or malevolent purposes compared to the heroic Superman in the main DC Earth.
300 isn't a DC comic. It has its own independent creation and doesn't fall under the DC Comics universe. The story and characters are distinct from DC's offerings.
Vampirella wasn't a DC comic. She has her own independent comic series and background separate from DC's universe. DC has its own array of characters and storylines that don't include Vampirella.