Because it's the weekend...

Teratorn or condor skull? I don't know, I'm just guessing.

Dodo...or a Terror Bird from South America.

Is it the skull of a razorbill Alca torda?

Looks like it's been beat up a bit. Are there any birds that lack a postorbital bar in life?

I would say the skull of a gull (Larus) or similar...

Fratercula arctica or Atlantic Puffin perhaps?

A great auk? (or a ropen...)

Puffin?

AFAIK no Dodo skulls have preserved rhamphoteca.

Looks like either the skull of a razorbill or a griffon vulture... but in either case, it would have to be missing the beak sheath on the lower bill.

is it a lammergeyer skull?

At first I thought it was an eagle of some kind, but puffin now seems more likely to me. I can't say which species though, but probably Fratercula arctica.

It's not a dodo. Has to be a falconiform or New World vulture.

Are there any birds that lack a postorbital bar in life?

What? All of Neornithes, if not, like, Euornithes lacks it.

Aquila chrysaetos ?

I'm in the Puffin camp, too...

The bird has two features which prevent it from being a raptor, at least: It lacks a palpebral projection lateral to the orbit, and it possesses distinct frontal fossae, which is distinctive enough to be features typical to procellariiforms (and sphenisciforms, if I recall correctly). The rhamphotheca, even from this angle, shows ornamental ridges/groove on the surface, which is definately procellariiform/sphenisciform. So, I'd say penguin or puffin/auk, and likely an Auk, in my eyes.

A Ceratopsian, or parrot, or something related to the parrot?

Razorbill? I don't think it's a puffin.

It isn't a Falconiforme. I'm going with Puffin, though Razorbill is possible.

We have puffins up here. The beak seems too shallow to be any puffin I've seen.

Auklet?

Pygmy hippogriff.

It's not a boneless aquatic pterosaur because this thing had, you know, a headbone.

My money is on Charadriiformes

Some species of owl, the beak should be a bit more pointed.

Oh, man, yes. Thanks, Jaime. It's got to be Fratercula.

I think it's a condor, because it's a big-ass skull (and condors are the heaviest flying birds) it's got a raptoral hooked beak, and it's obviously recent, not a fossil (my opinion, for whatever it's worth.)

Cathartes aura or Sarcorhampus papa, more problably the later

but don`t know if the red beak of king vulture remains on death, if not, is an andean condor...

I think it's some kind of Cathartid, and second Edgar's suggestion that it's probably Sarcorhamphus papa.

Actually, the beak is way too small for Fratercula. So I'll just jump on the cathartid bandwagon.

Great Auk (Pinguinus impennis).

Immediate impression was of an auk and most like a Razorbill (Alca torda). However the skull's overall robustness and the laterally thicker, blunt-tipped beak (Razorbills not surprisingly have a more laterally compressed razor-like beak) along with the multiple thin white lines running vertically down the bill sheath are more characteristic of a Great Auk. Most Razorbills (nominate subspecies?) have a single thicker vertical white stripe on the beak but I believe there is a subspecies that can have multiple thinner striations.

The specimen is not a fossil because it still retains the keratin bill sheath.

Harpagornis moorei (Haast's Eagle)? I know Jaime's already ruled out the raptors, but thought I'd go with my gut instinct anyway...

For some reason I thought "skua". Anyways, it's frustrating that few sources have bird skulls figured in a frontal view.

I'm going with Great Auk too.

You watch Atomic Betty?

What? All of Neornithes, if not, like, Euornithes lacks it.

I'm clearly not up on my tetrapod skull anatomy.

What would the rear margin of the orbit be called, and doesn't it look a rather bit like this skull is missing it?

I am already too late as answer has been given, and wouldn't have known it.

But I know that 'skua' is 'auks' spelled backward. :-)