Given the body weight ratio, I would hate to see the cat that could take out a full-grown possum. And raccoons can also kill them. No, they don’t PREDATE them (they’re not killing for a meal a la a red-tail or a coyote) but they can mangle or kill them. Possums in particular are nasty creatures, and the fewer of them in one’s barn the better. And again, a coyote needs to get lucky to take cats–they will if they can, but cats climb. An open field, the coyote can outrun them, in a situation where the cat can go up, the coyote can’t follow.
As Thomas says–a BARN OWN (this is a SPECIES name–there are dozens of owl species, it’s not “an owl”) isn’t going to kill a cat. It might if it got really lucky break one’s back but unless we’re talking newborn kitten I doubt very much it could carry one off. Barn owls kill small rodents (we’re talking mice here). If they got into a tangle with a full-grown cat it’s fifty-fifty who’d come out in one piece.
Given that in our experience you practically have to beat the livetrap with a stick to get a skunk to even notice you (we have one who traps himself on purpose for the bait and shelter and waits patiently to be let out in the morning) I can’t see a cat being killed by a skunk even in a defensive situation where the skunk felt threatened. They have…uh, other means of scaring off predators.
Red-tailed hawk or the larger buteos (the ones big enough to take rabbits, for example), maybe a great-horned owl (or an eagle owl if you’re where they live) could maybe take a cat if they had the chance. They’re big enough. Your average North American owl species (Barn, Screech, Barred, etc) isn’t likely to try, and the two teenies (Sawwhet and Boreal) could probably be taken out by a large enough cat who got lucky.