The origins of the Dark-Crawler are unrevealed, however it is clear that he is an extra-dimensional entity referred to as the Dark-Crawler's Dark Dimension. At some point in time the Dark-Crawler became the bitter enemy of the Undying Ones due to the function of his Dark Dimension, which allows access to other dimensions and planets. The Undying Ones tried multiple times to annihilate Dark-Crawler, but he killed every enemy sent by them.
Dark-Crawler was created by Roy Thomas and Herb Trimpe. He first appeared as the Night-Crawler in 1970's The Incredible Hulk #126, but later became known as the Dark-Crawler in 1982's The Incredible Hulk #269 in order to avoid confusing him with the X-Men's Nightcrawler.