Two of my rabbits are named for the color of their fur, Smokey and Pepper. My third is named Fred because my daughter named him after a character from Harry Potter. For black rabbits, some of the names I've heard that I like are Soot, Salem, Coal (Cole), Pitch, and Midnight (my childhood friend had a cat named Night-Night). Do you have any favorite characters from books, movies, or TV shows? I made a list of names once that included Winston and CeCe and then realized they were characters on one of my favorite shows, New Girl. You could pick a name that describes their personality or behaviors. The only example I can think of for that right now is Digger, but maybe if you watch them for a while, something will come to you.