A Bear. A big one, too.
A cheetah. Outrun that you pansies!
If I could choose, it would be either a horse or a cat. If it was a cat I think it would be plain old felis domesticus. I love my cats.
If it was a wizarding animal, the horse might become a hippogriff, or a pegasus, if there are such.
Thanks. Now why didn’t I remenber that? It’s been too long since I read the book, so I’m trying to remember what was on the screen. I definitely remember someone having a cat.
Damn, now I’ll have to read the book again. 
Umbridge’s Patronus was a cat, of course, as was McGonagall’s. Luna’s a rabbit and Lily and Snape’s does. Mr Weasley’s is a weasel and Ernie MacMillian’s a boar.
Tonks’ Patronus changed of course, from something unspecified into a wolf, after she started crushin’ on Lupin.
Can I have a smilodon? For a fantasy creature, a unicorn would be appropriate.
luna had the rabbit… did ginny have the cat?
i like polar bears and panda bears and tigers. the polar and tiger would be good. the panda would no doubt ignore the dementors and go to the nearest bamboo source.
Wile E. Coyote.
I’m so screwed.
Mine would be Barry Bonds. Dementors would so be giving me a free pass.
Chuck Norris.
A wombat.
Ginny sounds about right. I still need to check.
I think mine would be a frog, or a killer whale.
But probably a frog, one of the cute little thumbnail size ones.
Oh yes I am screwed.
I don’t suppose we’d be allowed to choose, but I’d like a fossa.
a humoungous walrus
Mine would almost certainly be an elephant.
Ginny’s was a horse. Luna’s was a hare.
I think patronuses have to be animal–I sort of vaguely equate them with daemons in the His Dark Materials books.
Mine would be a she-wolf, I think. Or a badger. Badgers are cool. I really like the otter, too. Hmmm…
Penguin?
I do like fossas. Or Foosas, as I more often hear them referred to. (Incorrect, but I hear it more often.)
Probably either a hare or a Standard Poodle. Most probably a Standard Poodle. They’re magical beasts, after all.
(See: Prince Rupert’s Boy)
If a fantasy animal… Something doggish, still. The dragon from Neverending Story seems most appropriate.
While we’re listing them off, Shacklebolt’s was shown, too. The book’s back at the library now, but I think it was an ocelot. And Aberforth, of course, had a goat.
Shacklebolt’s was a lynx, that came and gave them the warning, among other appearances.
ETA: Oh, and I think I’m in love with fossas. Never heard of 'em before tonight.