Harry's Pets (and Bob)
PB is a gray Maine Coon Cat
Mister:
Mister is Harry's cat that he rescued as a kitten from a garbage can three years before Storm Front. Mister's tail was torn off as a kitten, which Harry theorizes was done by a cat or dog that the newborn had run afoul of. Harry took him home, nursed him back to health, and kept him ever after. As an adult, Mister is about thirty pounds with a long gray coat. He's fond of bulldozing people's knees upon their entrance to Harry's house and sometimes acts as a vessel for Bob during reconnaissance missions. His size leads Harry to believe he might be a hybrid cat with wild cat ancestry. Like all typical cats, Mister is lord and master of Harry's home, contrary to whatever the wizard may think.
Bob:
Bob is a spirit of air and intellect housed in a human skull. He serves as Harry's "portageek", an incredibly vast source of magical knowledge and lore. He has a flawless memory as a spirit and will forget nothing unless ordered to by his master, but also has a problem distinguishing moral right from wrong. He appears in the skull as flickering orange lights in the eye sockets, but is capable to leaving the skull with permission from his current owner. Outside it, Bob is nothing more than a cloud of glittering orange light that is capable of "riding" with other creatures. While being a passenger, Bob can give his host protection against psychic attack, as seen when he defended Karrin Murphy from the collective will of the Lords of Outer Night in Changes.
Part of Bob's extensive experience and knowledge comes from his experiences by being owned by other wizards in the past. The most memorable was his owner before Justin DuMourne: Heinrich Kemmler. Kemmler was a necromancer who was the actual instigator of World War I, and creator of the Darkhollow, a necromantic ritual that can turn the successful caster into a demi-god. During Dead Beat, Bob is forced to unlock the memories of Kemmler and the Darkhollow, of which Harry tells him to forget completely at the end of the book.
When he's with Harry, Bob is jovial and blithe, with an unerring love of all things sexual. Harry often bribes the spirit with tawdry romance novels in order to get information the spirit might be unwilling to part with, especially if they have women in them. Being asexual as a spirit, Bob was once asked why he preferred women so much. His answer? "Because they have BOOBS, Harry!"
Breed is Caucasian Sheep Dog
Mouse:
Mouse starts off as a one of a litter of Foo/Temple Dog puppies Harry was hired to rescue by the Tibetan monk, Brother Wang. He hid under the passenger seat of the Blue Beetle and wasn't discovered until the monks had long since departed on their plane. Mouse earned his name because, at the time, he could fit in the pocket of Harry's duster with ease. However, as we see in later books, Mouse has grown from a fuzz ball to a fuzz barge. At a year old, he stands shoulders-to-waist on six-foot-plus Harry, and the vet believes that he'll grow to be even bigger. Aside from being tall, he also has a broad build. Mouse's coat is dark grey, marked with black on the eartips, tail and lower legs with a broad chest and powerful muzzle.
Mouse has displayed uncanny, human level intelligence through the series. From faking being injured to teach Harry's apprentice Molly a lesson, to being able to manipulate doors and objects, to keeping some of Harry's houseguests from killing each other by sitting on them until Harry arrived home. As a Foo Dog, his testimony is considered beyond reproach by the White Council, and he has exceptional skill in detecting and fighting evil entities. When confronting an enemy, Mouse's body will begin to shed blue and gold sparks of light from his fur and jaws and his growl can shake the floor around him with its intensity. He is exceptionally resilient, being hit by a van at nearly 30 mph and being only winded and a little dizzy after he gets up.
Characters with the ability to communicate with animals should be able to speak with Mouse as if you would a normal human being. He is exceptionally protective of Harry, but otherwise rather laid back and observant.