Subject says it all, really. We’ve covered fictional American Presidents before, so let’s hear about the rest of the world!
The character must be fictional but the position need not, so John Goodman as King Ralph and Paul Eddington as Jim Hacker count, but Helen Mirren as Queen Elizabeth 2nd and Meryl Streep as Mrs Thatcher do not.
The Duchess Gloriana XII of Grand Fenwick, from The Mouse That Roared by Leonard Wibberley (and the movie starring Peter Sellers). Grand Fenwick’s flag has a double-headed eagle saying “Aye” from one beak and “Nay” from another. Sir Roger Fenwick, English knight and founder of Grand Fenwick, recorded that he only learned three things in his two years at Oxford University:
That “Aye” might be turned into “Nay” and vice versa if a sufficient quantity of wordage was applied to the matter.
In any argument the victor is always right.
Though the pen is mightier than the sword, the sword speaks louder and stronger at any given moment…
I’m afraid I actually like the portrayal of Grand Fenwick’s entire gov’t more than just the Duchess, though.
King Rudolf of Ruritania
Havelock Vetinari.
The “rest of the world” can be a fictional world, right?
King Richard IV (Brian Blessed), father of the Archbishop Edmund Blackadder
Prince Akeem Joffer of Zamunda.
Nicolae Carpathia from the “Left Behind” series. I mean, Satan himself, am I right?
Victor Von Doom of Latveria.
Emperor Gregor Vorbarra of Barrayar from the Miles Vorkosigan novels by Lois McMaster Bujold
John Carter, Jeddak of Jeddaks 
Let’s keep it to the real world, please.
I was impressed with the British Royal family in “World War Z” (the book). Does that count- a fictional portrayal of real characters, or so we assume; they’re not called out by name.
nm
Why?
I’m pretty sure the thread title says “fictional”.
Same for Nevil Shute’s novel In The Wet.Liz and Phil and little Chuck are not named, but are unmistakeably themselves.
I can’t think of many fictional foreign leaders, good OR bad.
My favorite… I dunno, Aragorn was probably a pretty good king.
King John IV, in Randall Garrett’s “Lord Darcy” books and stories. (And I’ll put in a plug for Michael Kurland’s treatment of the character, in “A Study in Sorcery” and “Ten Little Wizards.” Very true to Garrett’s original view.
Muskar XII of Syldavia, in the Tintin adventure “King Ottokar’s Sceptre” by Herge.
And I can’t remember the name of the emperor, but the great alliance/state/empire of Scythia-Pannonia-Transbalkania, in Avram Davidson’s “Doctor Eszterhazy” stories is a wonderful place, and the stories are delightful.
Does Fu Manchu count? He is the unofficial leader of the Si-Fan, a consortium of secret societies far more powerful than many actual nations!
Kim Jong Il
…what?