Hybrid animal monsters are more art than science.
Owlbear. Weird, but fine. Classic, in any case.
Hawkwolf. Maybe it has bigger front talons? Better vision in addition to scent? Otherwise hard to see how it’s much more dangerous than a wolf.
Cobratiger. Okay, that gets us someplace. Tigers are dangerous enough without being poisonous. A spitting cobratiger is extra terrible.
Sharkorpion. This has gone all the way past cool back to goofy Syfy Movie territory.
That said, it would terrify adventurers in an aquatic campaign.