In the Soul Calibur 5 you are able to unlock different types of playable characters that you can use during the campaing and take them online. See below the characters that are unlockable and how each chacter can be unlocked.
Dampierre: You will get the character through Best Buy pre-order in America and the Europeans can have it as a part of collector’s edition. Otherwise, you will have to wait for the appropriate DLC with this character.
Alpha Patroklos: Unlock this character when you complete the story mode with any character.
Elsyium: She will be unlocked on the completion of story mode with any character.
Algol: Defeat Algol in the Legendary Souls mode and then complete the mode to unlock the character. You can also unlock him by defeating him in the quick battle as the opponents Teramos or Minami Naikos.
Edge Master: Story Mode completion with any character and will unlock Edge Master.
Pyrrha Omega: Completion of story mode with any character.
Kilik: To unlock, defeat him in the arcade mode with any character using the Asia route. You can also unlock him by defeating him in the Legendary Souls mode and then completing the mode.