Odd Thomas/WMG
Make wild guesses for Dean Koontz' Odd Thomas series here.
There are no such things as ghosts; Odd is both psychic and dangerously unhinged.
Aside from an english transfer student who was hit by a truck minutes after they met, Odd is the only one in the series who can see the ghosts and bodachs. It's possible that, as an effect of the Midnight Train project in the Christopher Snow mysteries (alluded to being in the same 'verse as this and Watchers), Odd is temporally unstable. He can know details of the past, such as what a person looked like the last time they were alive, and when something really really bad is going to happen. The ghosts are merely a response to his inability to comprehend more than the present at any given time. It may even have allowed him a response to something particularly traumatic in his past: His mothers suicide and attempted murder of him. Successful suicide. She never talks to anyone else, or really leaves her house, and others either don't want to ruin what appears to be a healthy (if hallucinatory) relationship, or nobody's noticed that he thinks she's still alive, and he never listens when they refer to "the late Mrs. Thomas." Hey, it's happened before... "Stormy" even "talked" with him post-mortem, and he admitted that her voice was all in his head. Who's to say he wouldn't prefer his mother right here for the rest of eternity, or at least not in Hell, with Stormy waiting for him in their next life?) Elvis, Boo, and Frank Sinatra are there just to help him cope. That's why Elvis And Sinatra can change age and clothing, and why Boo is even still around, considering he's seen no other ghost animals). The english kid was just messing with him or had some sort of sympathetic ESP (or both), and the Reaper was actually a physical aspect of Brother John, as a result of the Quantum Thingummy. Not a hallucination at all. Oh, and Annamaria is a time cop (not, in this guess, a Time Lord), protecting Odd from the sentient and malevolent coyotes that usually exist a few microseconds in the past and/or future.
Dean Koontz picked a quirky name for Odd Thomas after hearing about another famous Odd.
If it turns out Koontz created his Odd character first, then it was time travel. Or a wizard. It's the only logical explanation.
Boo was one of the Francis Project dogs from Watchers.
Odd has never seen any other animal ghosts because no other animals are intelligent and self-aware enough to feel they have unfinished business or whatever it is that keeps a ghost from moving on.
Odd Thomas is on his way to Moonlight Bay.
Firstly his attire in the beginning of Odd Hours: a Wyvern sweatshirt and a Mystery Train cap. He'd said he didn't know why, but he'd felt drawn to them. Psychic Magnetism of course! Secondly the coyotes that weren't what they had seemed. We see such creatures in Seize The Night, and there's nothing implying that they had ended up psychologically imploding like some of the other animals yet. One must also consider that Odd Thomas finds himself stopping bigger and bigger crises as he goes on in his life. The crisis present in the Moonlight Bay books is definitely catastrophic on a worldwide scale. Third: We've been waiting over a decade for Ride The Wave to finish off the Moonlight Bay trilogy. Koontz has called it "delicate". Of course it is. It's about to directly cross over with his Odd Thomas series! Oh, and finally, the title of the 5th Odd Thomas book? ...Odd Apocalypse.