What are some young princes (or royalty i.e. baron, heir) in the world today?

For instance, what are some youg princes under the age of 18? They don't have to be like, prince-next-in-line-to-the-throne, just someone royal, or extremely close to it. Like a lord, or a baron, or count or what ever! They can be from any country, so long as they are under 18!! Please help!!