Jared Leto as Prince Eric:
What mermaid -- or human -- alike hasn't at one point succumbed to a guilt (or not so guilty) crush on Jared Leto? He's got those luscious long locks and whirlpool eyes but at the end he'll probably wind up ditching Ariel to be with Princess Lupita Nyong'o -- or because 30 Seconds To Mars is going on tour.
Kathy Bates as Ursula:
The most obvious choice. Kathy Bates was terrifying as Madame LaLaurie in American Horror Story: Coven, painting her face with the blood of her tortured slaves among other horrific things, and with the right purple hue and ominous jazz hands, she would definitely kill as Ursula too.
Robin Thicke and Terry Richardson as Ursula's Pet Eels:
Miley Cyrus as Sebastian:Miley is SUCH a frisky crustacean.
Morgan Freeman as King Triton:The only actor with enough godly power and smooth seductiveness to play both Ariel's merman-daddy and king of the entire ocean is Morgan Freeman. He rocked the all-white suit as God in Bruce Almighty, and would be equally fierce wearing gold cuffs, a flowing beard, and a trident.
Jonah Hill as Flounder:
Aside from their shared baby cheeks, both Flounder and Jonah Hill make for epic wingmen. Flounder's extreme anxiousness and buffoonery throughout the Little Mermaid is just like Jonah in Superbad, right...? Also just imagine Jonah Hill swimming around in a striped yellow and blue onesie.