Nouns:
* Darkroom: A room used for developing photographs.
* Dark horse: A person or thing that is unexpectedly successful.
* Darkness: The state of being without light.
* Dark matter: Hypothetical matter that cannot be seen but is believed to make up most of the matter in the universe.
* Dark side: The opposite or negative aspect of something.
* Dark web: A part of the World Wide Web that is not indexed by standard web search engines.
Adjectives:
* Dark-haired: Having dark hair.
* Dark-skinned: Having dark skin.
* Dark-eyed: Having dark eyes.
Verbs:
* Darken: To make something darker.
* Darken the door: To visit someone's house, especially unexpectedly.
Phrases:
* Dark ages: A period of decline or stagnation.
* Dark cloud: A feeling of sadness or pessimism.
* Dark secret: A secret that is kept hidden and often shameful.
Other:
* Dark chocolate: Chocolate with a high cocoa content.
This is not an exhaustive list, but it provides a good starting point for exploring compound words with "dark" in them.