Ok, so Settlers of Catan or just 'settlers' as it's frequently known is a strange name for a game. Here are the top three name-related questions people send in over and over:

1) Where is this Catan everyone is talking about and why make a board game and a card game out of it?

2) Is it properly spelled Catan, Cattan, or maybe even Katan or Kattan?

3) Is The Settlers of Catan the same game as Die Siedler von Catan and other similar non-english names found around the web?

Answer 1)
After researching this one for quite a while it seems that Catan is purely fictional. Some people have taken the mythology of Catan so far as to write up fan fiction about the origins of Catan and how it came to be. One author, Rebecca Gablé, went so far as to write a full novel entitled, Die Siedler von Catan (2005), (in German).

Answer 2)
Although I've seen all of these on the internet, the correct full version is Catan. Starts with a C and has only one T. If you google around you will find a lot of the other versions but when you want to get the real information, Catan is what to search for.

Answer 3)
As settlers is originally a German board game, and since its become so popular, you will find references to not only Die Siedler von Catan (German), but a raft of other names for versions in other languages such as:

Colons de Katane, Les
Die Siedler von Catan
Siedler von Catan, Die
Kolonisten van Catan
Descobridores de Catan, Os
Coloni di Catan, I
Catanin Uudisasukkaat
The Settlers från Catan
Colons de Catane, Les
Catan Telepesei
Los Colonos de Catán
Los Descubridores de Catán
Katanas ieceïotâji
Osadnicy z Catanu
The Settlers fra Catan
Katan no Kaitakusya
Osadníci z Katanu
Catan - Landnemarnir
Naseljenci otoka Catan

All of these are the exact same game, just with localized translations.

For some more background info, check out the publisher of Catan's corporate site.