The Littlest Pirate King is David B and Pierre Mac Orlan's 2008 kids' comic about a living child who is adopted by the damned pirate crew of the Flying Dutchman, who sink to the bottom of the sea every day at dawn, and rise every night at dusk to murder and terrorize and try as best as they can to smash their cursed ship to smithereens and end their eternal damnation.
At first, the crew spares the baby so that they can raise him to adolescence before murdering him and making his ghost into their cabin-boy, but they quickly become sentimentally attached to him, and can't bear to kill him. In the end, they send him back to the land of the living -- a strange place he fears and loathes -- and leave him howling and abandoned on shore, begging them to kill him and make him undead like his friends.
So, it's a little grim.
But it's also gorgeous. The seas of Littlest Pirate King are filled with monsters and huge fish and wrecks and strangeness of all sorts. Each page is more gorgeous than the last, and the fantasy sequences in which the dead pirates parody the land of the living for their boy are perfect in their monstrosity. (just page through the image-search for some previews)
If you liked the premise of Neil Gaiman's award-winning Graveyard Book, you're sure to love this, but be aware that it's much a darker and sadder story than Gaiman's. I think this is probably suited to kids eight or nine and up -- my five-year-old loved it, but burst into inconsolable tears on reading the last panel, and I had to read her the entirety of Art Baltazar's loony Superman Family Adventures twice before she'd get to sleep.