dark cloud of interstellar material, often in the form of a diffuse nebula. These clouds, if very cold, may contain simple molecules ( molecular clouds). Although containing both gas and dust, the micro dust (10-100 nm) component can dim and often block the passage of short wave radiation (e.g., light) through the cloud though longer waves (infrared and radio) can usually pass through.
A cool cloud of dust and gas. Due to its low temperature it does not emit light in visible region of spectrum so appears dark, often blocking out light from stars that are behind it. Best example is the Coal sack nebula in Crux.
A dark nebula is a type of interstellar cloud that is so dense that it obscures the light from the background emission or reflection nebula (eg. the Horsehead Nebula) or if they block out background stars (eg. the Coalsack Nebula).
Dark Nebula (Dark Zero in the original Japanese version) is a fictional character in the Kirby series of video games for Nintendo. He is the final boss of , and the true villain of the game. He commonly appears as a giant black star with a purple glow/flames around his body and a red/pink/purple cat-like eye in the center.