Number of characters ?

[GreenKnight]

Max Number of characters ?

How many characters can I make ?

Will I run out of space transferring from Frostmourne ?

[dman3232]

If you go to My Account -> Barracks select your realm, and look at the bottom, it tells you how many character slots you have total and how many you have active. You can deactivate characters which takes them off the selection screen in the game but doesn't delete them. For instance on icecrown, I can have 10 active characters with a total of 50 characters (so 40 inactive and 10 active maximum).