Price, the Raven
"Poet, thespian, messenger of the underworld:  no ordinary raven, me." 
Perched upon the arm of Death himself, this supernatural Raven speaks for silent Grimm.... though not always what the reaper would intend.  Price is Grimm's herald and constant companion, a chattering ebony-feathered specter — and oft nuisance — that is the closest thing to a friend old Sam has ever known for eternity.
Price has seen it all and knows too much — and the Pup is an unexpected novelty.

Sam Grimm, the Reaper
"..."
Silent death:  inevitable, inexorable, relentless — Grimm is its embodiment, the reaper of souls, dark ferryman of the underworld, the dread specter of mortality.... why should one small puppy vex him so?  Grimm just knows that persistent kook, Doktor V, is somehow involved.  Why must it always be V...?
The work of the reaper is a thankless burden.

Peck. the Vulture
"I'm the bird with the plan... lotsa plans... And I'll get em... you'll see... I hope... hey, where'd he go?"
Peck is the most pathetic of a flock of scruffy vultures:  a loser among losers, a bullied dope desperate to prove himself to his lackluster peers.  Obsessively scheming and planning, Peck isn't afraid of failure — though maybe he should start.  Poe is a prize he spotted while the Pup was still alive and alone in the stormy wood, and won't stop until he gets the now undead Poe, somehow, no matter what it takes.... and really doesn't grasp how bad an idea that may be...

Munch, the Maggot
"A maggot is a friend to everyone... in the end." 
Munch met Poe during the Pup's brief dirt nap — but this cheerful fellow never got the chance to nibble, literally having his meal walk away while caught up in a revery about the feast before him.  He has followed the zombie Pup ever since, becoming Peck's unlikely friend and foil in the process.  Munch is an amiable gourmet among maggots, a worm of good breeding with a refined palate and exquisitely revolting taste.  Now, if Poe would only remain inanimate long enough to stay for dinner.

Doktor V, the Veterinarian
"They called me mad.  But I will prove them wrong!  Is it mad to seek the essence of life?  Is it mad to dabble in the laws of nature?  IS IT MAD TO REANIMATE GOLDFISH IN THE NAME OF SCIENCE?!  NO!  I AM NOT MAD!  WAH-HA-HA-HAAAAA..."
So he did end up a small-time veterinarian in a tiny town — Doktor V will still uphold his family tradition and prove himself worthy of his ancestors' scientific legacy.... but his one success keeps getting away. 

Polly-Ann, the Sweet Little Girl
"Let us all be friends and have ever so much fun!"
The little girl who wuvs Poe so.  The Pup was her birthday gift, lost one dark night and almost forever.  But in life or unlife, Poe is her dear puppy, and Polly-Ann really hasn't noticed much difference. 
Even on the stormiest night, the sun shines just for her.

Poe, the Goodbye Puppy
 "WOO..."
Poe was just an ordinary puppy, but one stormy night he wandered off, and was all but gone. Polly-Ann rushed the Pup to the pet clinic of Doctor V, but even the veterinarian's best efforts, even a shot of his experimental vivifying elixir, was not enough. Poe was buried in a simple shoebox under the flowers of the family garden. But in the dead of night, the little grave was found disturbed, the box empty.
And then, quite unexpectedly, Poe came back...