Griffon, Shadow & Nightmare are Familiars wielded by V.
Griffin is a demon bird with a beak split into three pieces and a black with blue highlights color scheme based on Griffon.
Shadow is a pitch black panther demon based on Shadow.
Nightmare is a hulking monstrous demon composed of sludge and with a single eye loosely based on Nightmare.
Griffon is a extremely talkative and wise cracking bird not shy about snapping at V or other characters or making digs at their expense. Shadow maintains the personality of a attack dog, waiting for V to give the order before loosing his attacks. Nightmare is the most difficult to control, he does not respond to orders and when summoned acts according to his own intuition.
Though loyal to both V and Vergil they recognizes that their continued existence will only bring him pain, so once they have outlived their usefulness they intercepted and attacked Dante forcing him to kill them.