When you have a 100% game completion the following bonus characters will become available.
Elrond (2nd Age):
Have a 100% game completion to get this half-elven character.
Newborn Uruk-Hai:
Have a 100% game completion to get this Orc that serve Sauron and Saruman.
Cheat Codes
When you reach Bree look for the merchant cart at the entrance, Talk to the merchant cart to access the in-game shop where one of the options on the men is 'Codes'. Enter the following codes to enable the corresponding effect.