Willpower
Willpower is the core stat for most Mental Disciplines, along with Blood Potency. It helps in controlling the beast, but how much is up to GM discretion.
Example values
Animals
Can be expected to have a Willpower of 1 or 2, possibly a 3 in very exceptional cases.
Humans
Human willpower varies between 1 and 5 approximately based on Maslow's hierarchy of needs.
Ghouls
Ghouls have the same willpower as their base creature.
Kindred
Kindred never have less Willpower than Blood Potency, and there is no known upper limit.