He is (and the Reel Them In ability is based on his anchor toss) but he lacks the cheesy Halloween-ness of Captain Cutler's Ghost :P
I shall PEACH your Mawkin (which sounds vaguely dirty) below!
Let's see...I really like the level 0 "resurrect into the class" idea. You should specify if it gives you any penalties or has a time limit, though, and you currently have it granting save bonuses at level 0 before you actually take the class.
Kinda weird that you suffer a disguise penalty for your shadow but not your demonic plant head. I like the shadowy grapply thing though, very evocative.
I like Mawkin Form. I think it might not last long enough to truly make an impact compared to barbarian rage, although it is quite a bit stronger so I'm not sure.
Stalking Midnight is a good idea but as written it basically alerts people to your presence while you're trying to sneak-up on them. Maybe make it so you can designate targets?Annnnndddd I'm an idiot who didn't see the "when you attack" part, ignore me.
Any particular reason for the "not in alternate form" restriction on Eerie Gaze?
Lurking Visions seems to have backwards fluff: People that can't detect you suffer a penalty because they see you :P
Secret Terror is nice but not particularly impressive as a capstone ability. Not sure what I would add except letting you identify casters like you can with Whispers in the Night. Maybe a type change to undead or plant (can never have enough plants!)?
All-in-all, I like it. My only problem is it doesn't seem sure whether it wants to be a stealth class or a combat class. It has some great combat abilities but meh HD and 3/4 BAB. Also some great stealth utility but only decent skills and none of the great rogue ones like Disable Device/Open Lock/UMD. You should clarify how the fear abilities stack/interact with each other and the Intimidate skill too.
Looking over it now, I'll write something up when I get a chance!
EDIT: PEACH for the Horror is done, see the box in my next post!