Depends on who you know, doesn't it?
Trish - A sexy blonde woman who knocks Dante's wall down and stabs him with
his own sword. She was created by Mundus especially to look like Dante's mother.
Trish drags Dante to Mallet Island where she says that Mundus is planning another
bid to take over the human world. She betrays him in the middle of a battle
against Nightmare, and afterwards, when a piece of stalactite is about to fall
on Trish and crush her, Dante saves her only because she resembles his mother.
She also steps in the way of a blast by Mundus to return the favor. Later, even
though she appears to be dead because of the blast, Trish gives her powers to
Dante so he can blast Mundus one last time and get off of Mallet Island. Lastly,
Trish becomes his partner in his renamed business, Devil Never Cry.
Mundus - Evil demon with ambition who fought Sparda, Dante's father, two thousand years ago and is making another try. He is also responsible for the death of Dante's mother and enslavement of his brother, Vergil.
Vergil/Nelo Angelo - The Black Angel. He first appears by walking out of the mirror in the castellan's bedroom in Dante's own form. Could have been his own form since they are twin brothers. You battle him three times and he shows his real face. Vergil shows his presence with blue crackling energy. Apparently Vergil was not as dead as Dante presumed him to be.
Sparda - Dante's father. He is said to be full of righteous fire according to Dante's mother. Sparda put a halt to the uprising by Mundus two thousand years ago, and apparently the family resemblance is quite strong between father and son.
Lucia - Lucia is a member
of the Protectorate, a race of half-human, half-demons who protect the island
of Vie de Marli. Her adoptive mother, Matier, found her when she was just a
little girl and raised Lucia as her own. However, she seeks out Dante's help
when Arius, leader of a major public corporation, seeks to become a demon himself.