The informal adjective extraordinaire is a great way to describe someone who does something particularly well. You might describe your sister as a dog trainer extraordinaire, for example.
If you know people who are truly outstanding at what they do, you might want to use extraordinaire when you talk about them. You could mention your neighbor, the cupcake baker extraordinaire, or your uncle who's an amateur magician extraordinaire. In either case, you're emphasizing how good they are at their particular talents. Extraordinaire is a French word that means "extraordinary, unusual, or out of the ordinary," and it's been used as a superlative in English since the 1940's.