King Shark is a villain from the massive pantheon of DC Comics' world. Depending on which canon you choose, King Shark has been depicted as the offspring of a Hawaiian shark god, a marine biologist mutated in a horrible scientific accident or a poor deformed soul coerced into joining Amanda Waller's Task Force X. Regardless of origin, King Shark is a formidable foe, possessing extreme strength and durability, razor sharp teeth and claws, regenerative abilities and is able to travel through water with the speed and grace of a shark.
For King Shark's first speaking appearance in Batman: Assault on Arkham, John DiMaggio was cast as the ferocious fish. John's King Shark is more of a dumb brute - a physically massive, mutated person with sharp teeth, claws and gills. And whether or not this was deliberate, John's slow and simple manner of speaking, to me at least, helps convey the sense of a creature that's not used to speaking, and instead is more accustomed to being underwater.
In Lego Batman 3: Beyond Gotham, yet another deep-voiced veteran of the industry lends his talents to The Shark: Travis Willingham (or should I say, Travis Gillingham, amirite?). Though, unless I'm mistaken, all he does his grunt and growl, so sadly, he won't be included here.
David Hayter voiced King Shark in his live-action role on The Flash. David plays King Shark as much more of a feral, monstrous beast, as evident not only in his physical appearance, but by the heavily-modulated and growly voice he has.
In DC Super Hero Girls, Kevin Michael Richardson steps up to the mic. Kevin gives a suitably growly and monstrous performance to his King Shark, but unfortunately, comes off as more of a generic beast.
I'm honestly not sure who to vote for on this one, since they all give varied and appropriate voices.