What animal can kill Megalodon?

What about reptiles?

I think that a mosasaurus has a good chance against a megalodon.

Crocodiles? 

Kronosaurus

Xenotaris other than Kronosaurus what else could go toe to toe with meg?

I will say that a box jellyfish could defeat it,because a box jellyfish isn't extinct,for an extinct sea creature,i would say Livyatan Mellivei.Livyatan Mellivei looks like a giant whale with sharp teeth,it has the same hunting tactics as the Megalodon,so...it will be a good match-up,also they have similar sizes.And the box jellyfish could poison the Megalodon.

The true shark Boy

Okay how about Kronosaurus's cousin? The Liopleurodon

Liopleurodon was way too small to kill Meg, for crocs Purussaurus, Sarcosuchus, Rhamphosuchus, Deinosuchus, etc. stand the best chance, due to their size and agility, especially against a smaller or juvenile Mega. Pliosaurus, mosasaurus, livyatan, Carcharocles chubutensis, other Megalodon, and Tylosaurus could also win. There’s also some other creatures I’m forgetting.

TheLazyFish (other than the four that you mentioned) what other giant crocodilians could give the megalodon a run for its money?

Bigger doesn't mean better TheLazyFish

I will say that a Purussaurus and a Rhamposuchus will kill the Meg.

BUT  LIVYATAN MELLIVEI WILL STILL KILL THE MEG!

I know that Xenotaris, but saying a Liopleurodon can kill a Megalodon is like saying a single Utahraptor can kill a Camarasaurus or an Ocelot can kill a Tiger. At a certain point a creature is too small to pose too much of a threat to a larger creature (without venom or other defenses like quills on a hedgehog). As far as we know, Liopluerodon possessed none of those. Seriously, a great white shark sized pliosaur to a Megalodon. No way.

well if the liopluerodon is desperate enough it prove to be a nuisance. Also wolves have been known to take down animals way bigger than it, so Utahraptors taking down a Camarasaurus isn't too far fetched. Some Utahraptors can grow to roughly the same size as an Allosaurus europaeus.

I said a single one, and a single wolf won’t scare off a bear, and the difference is that the Megalodon would be actively looking to kill the Liopleurodon, not escape like an elk. Also, I meant Camarasaurus supremus, the one that got to 60 feet. That’s why it’s far fetched. It’s also like saying a great white would kill a Megalodon, seeing as it’s only slightly smaller than Liopleurodon. Sure, if they’re incredibly lucky with a gill shot, it’s possible. But usually, they’ll just be eaten.