* Katelyn - The most common spelling.
* Katelynn - This spelling adds an extra "n" at the end.
* Caitlin - This spelling uses a "C" instead of a "K" at the beginning.
* Kaitlynn - This spelling combines the "n" addition from Katelynn with the "C" substitution from Caitlin.
So, there are at least four different ways to spell Katelyn.