I’ve always wondered about this. Off the top of my head, I can’t really think of too many world leaders who have been referred to (either in the media or history books) by their first names. Everyone knows who Roosevelt, Kennedy, Khruschev, Stalin, and Churchill were. However, I doubt too many folks refer to those aforementioned leaders as “Franklin”, “John”, “Nikolai”, “Joseph”, or “Winston”, respectively.
So why is the leader of Iraq almost always mentioned by his first name?? 
Partly to avoid confusion with the former leader of Jordan, King Hussein. But I suspect partly that calling him by his first name is a not-so-subtle way to show lack of respect.
Horsecrap. I’m really getting tired of seeing this question here.
Saddam is called by his first name because everyone calls him by his first name.
There was a news article years ago explaining that George Bush’s word “SAD-dum” is an intentional mispronounciation which means something slightly derogatory. Means “street vendor” or something? My memory is fuzzy.
There have been other threads on this. A lot of folks who try to answer it really don’t know the answer at all.
The Straight Dope of it is:
A lot of Arab names are first name + father’s first name, but no surname. Yes, though this may come as a shock, there still are lots of folks in the world, in several non-Western cultures and also Iceland, who get by just fine without any family names. In Saddam’s case, Saddam is his given name and Hussein (actually should be spelled Husayn) is his father’s given name. A patronymic. They don’t really have a family name. If their family were to use a surname, it would be al-Takriti (or maybe al-Tikriti, I’m not sure of the first vowel). But this is a place name based appellation, not really a family name.
habs:
I’m not trying to be an amateur moderator here, but before posting a question in the General Questions forum it’s always worth checking that it hasn’t been asked and answered already. You can use the search button on the SDBM home page.
Why is it Saddam? was launched on January 30, for example, and
Why is Saddam Hussein often called just “Saddam”? was launched in September last year.
You can use the search button on the SDBM home page.
I see a search button on every page.
I remember this. I was told that when GHWB pronounced it “SAD-em” it sounded like a term for “one who cleans shoes”.
Khrushchev’s first name was Nikita, not Nikolai. Carry on.
If this were true, then a) Americans would refer to other Arab leaders in analogous ways; and b) other English-speaking people would also refer to him that way. I haven’t seen evidence of either. And I understand the concept of patronymics just fine, since Russians use them in many situations, and I’m fluent in Russian.
Sorry, I meant to say “if this were the whole story,” not “if this were true.” I’m not at all implying that the facts stated aren’t true, just that they don’t fully explain the situation.
Eva Luna, some Arab families have family names, like al-Sadat, al-Asad, and ‘Arafat.
Many others don’t.
Confused yet? 
It’s just that family names are considered optional in that culture. It’s intermediate between the cultures, like Malaysia and Mongolia, where family names are never used at all, and Western culture, where family names are de rigueur. Those who have them use them, while those who don’t get by without.
I once knew a guy from the Shetlands. His name was Sweeney. That was it: it was his first name and his surname. His dad’s name was Sweeney too, and so was his grandfather’s, and so on back into the mists of time.
It caused havoc with computer systems, and ‘officially’ his name became “Sweeney Sweeney” - at least that’s what it said on his driving license. He then amended this to “Sweeney McSweeney” so that it didn’t look quite as odd.
This was covered in an earlier thread. Far as any of the experts could determine, it’s not true.