In Spanish it is normal for a child to take the father’s surname, unless it is a very common name, in which case the mother’s surname is tacked on as well, e.g. the playwright Federico García Lorca
Re: Dubya, MLS is correct. And he’s not a “Junior,” since his full name is George Walker Bush and his dad, POTUS 41, is George Herbert Walker Bush.
Why so many aw-shucks first names for dudes like Bill Clinton, Al Gore, Bob Dole and Tony Blair? Sheer populism. Just about every politico in a democracy wants to seem likeable and approachable to voters.
For what it’s worth, Clinton’s autobiography is credited to “Bill Clinton” (and Carter’s books to “Jimmy Carter”).
He went by Groover? Really? I didn’t know he was a hippy. Groovy! 
On the other hand, IIRC Abraham Lincoln hated to be called Abe, “Honest Abe” political slogans notwithstanding.
Did Bill, Al, Bob & Tony use their full names before they entered politics? Or did they just continue with the names they’d used most of their lives?
And occasionally a politician will use an opponent’s full name to stir up a little anti-populism. During the 1988 presidential campaign, George HW Bush insisted on referring to Pete DuPont as “Pierre” (his real first name) during debates to make DuPont sound like a ferriner.
So Rodriguez is his dad’s name, right? I just don’t see why it’s unusual for him to go with Zapatero since that’s indeed his last name - if you do take your mother’s name to tack onto your next-to-last-name, then you don’t go by it? It’s just for, like, differentiating you from all the other people with a common name, in the same way that a little kid with a common first name will be known by the name and his/her initial?
From personal experience, this nickname-preference thing is much stronger among Brits than among Americans. Most Americans I know might habitually go by a nickname or a diminutive, but they don’t generally avoid their full, legal names. However, on a handful of occasions I’ve dealt with Brits, if they go by a diminutive, they stick by it powerfully. I was once speaking to a British “Mike” on the record for an article. He refused even to confirm that his legal name was “Michael.” I’ve never had that experience with an American. They might say, yeah, it’s really “Michael,” but I prefer you print it as “Mike.”
That’s true. He usually preferred just being called “Lincoln,” and usually signed things as “A. Lincoln.” Come to think of it, Theodore Roosevelt didn’t like being called “Teddy” much.
I asked a buddy of mine why he called himself Bill, instead of Will.
He just shrugged. “Just the way it’s always been.”
Data says: “One is my name. The other is not.”
That’s interesting, Nava. I specified “English-speaking countries” because the large majority of non-anglophone politicians that I know are referred to by their legal names, at least when it’s printed in the paper or in similar places. Right now I can only think of one exception (other than Zapatero): Premier Jean Charest of Quebec is actually legally John James Charest. I believe he’s used “Jean” his own life, though, and it’s just another version of his first name, not a nickname or diminutive form.
The Latino tradition is <first given name> <second given name> … <nth given name> <father’s father’s family name> <optional hyphen> <mother’s father’s family name>.
Officially, everyone has a double-barreled family name. For casual purposes, the first (paternal) half of it is the important half and when in a hurry you drop the second part, not the first part-- So Fidel Alejandro Castro Ruz is “President Castro,” not “President Ruz.” Similarly Jose Daniel Ortega Saavedra.
He might well have been named “Mike” at birth. I don’t know about the USA, but in the UK it’s not uncommon for a diminutive to be the actual legal name, registered as such on the birth certificate.
And I’m aware of this possibility, but he strangely refused to specify this. Here, people say "My legal name actually is just ‘Mike’ " or “It’s ‘Mike’ on my birth certificate.” Very easy to clear up. This Mike was like the Seinfeld date who just shook her head. I think I even asked something like “So is ‘Mike’ your legal name?” and he refused to answer clearly.
What was he called other than “Data”?
I think it was “Data (short a sound on the first a)” if I recall correctly.
During the second season of ST:TNG, Doctor Pulaski kept pronouncing his name “Datta” instead of “Dayta”.
As to politicians, I’m pretty sure that my local congressman is not really named “Doc”
A former Washington congressman was known as “Scoop” Jackson: