When you're talking about a person, but not a specific one, use the word somebody. If you cook more than you can eat yourself, you might ask, "Does somebody want this extra macaroni and cheese?"
Interestingly, synonyms for somebody include "whoever" and "superstar." In other words, you can use this pronoun to mean any random individual, like when you suggest that somebody is likely to get hurt at a busy intersection near your house. But you can also use it for a very important, well-known, successful, or famous person: "I don't want to get stuck in this small town — I want to be somebody!"