monarchys

another question is whats a common name 4 them?

who are you talking about specificaly???
the british Royals?

Another question might be why are individuals usually given the same first name as those who preceded. I don't know the answer but it might be connected. Perhaps it's to strengthen the idea of dynasty.

Cherrymk - I hope I understand the questions.

Kings and queens have a number after their name to signify which one you were refering to- Henry VII was the father of Henry VIII. In their lifetime no one would say "let's go visit Henry VIII" - they would just say King Henry or The King. Same is true of Queens. Elizabeth I was the first woman to rule England with name Elizabeth. Today we have Elizabeth II, thus the second woman to rule England also named Elizabeth. You have to keep them numbered in order to keep their time lines straight.

They do have family names like Tudor or Windsor, but that is not the same as having the number.
Both King Henry's had the family name Tudor, but you still need the number to tell who was who.

King Charles I of Spain reigned from 1516 to 1556. He was also Holy Roman Emperor. For this title he was not Charles I. He was Charles V.