Zig the Hyena
- Animals Hate Him: Other animals on the island love to attack him.
- Anti-Hero: Believe it or not, he is this in some episodes, as the Jerk with a Heart of Gold variant. Likewise, he becomes this trope only when the other enemies are after Marina or when it comes to teaming up with Sharko. In other episodes, he is the Villain Protagonist.
- Butt-Monkey: He goes through ice and fire, but the next second he looks like if nothing happened .
- The Charmer: In Birthday Party, he manages a really good birthday party and acts like this to Marina just to eat her. Then Loony Cruise shows us that, with a tuxedo, he can make a woman fall for him.
- The Clan: In Desert Island Drought, he is shown to be from a large family of very successful hunters.
- Crouching Moron, Hidden Badass: He shows hints of it. In Desert Island Drought, he manages to defeat Sharko.
- Faux Affably Evil: He acts around Marina like a gentleman (ex. Birthday Party), but, of course, he's gonna eat Marina.
- Determinator: He won't stop at ANYTHING to eat Marina.
- The Dreaded: Some of the smaller animals fear him.
- Harmless Villain: He may always try to ingest Marina, but he's pretty weak and always fails at doing so.
- The Hyena: He always lets out a good laugh.
- Ineffectual Sympathetic Villain: His attempts at eating Marina are all for naught and he never catches a break.
- Jerk with a Heart of Gold: He genuinely considers Bernie a friend.
- Obsessed with Food: He is obsessed with eating Marina.
- Open the Iris: Whenever his hunger gets really bad. It is usually followed by an Oh, Crap! expression from Bernie.
- Red Eyes, Take Warning: Subverted, while he does have red eyes, he is somewhat harmless.
- The Scrappy: In-Universe, Zig is widely hated and laughed at.
- The Speechless: While Sharko and Marina are Speaking Simlish, Zig usually makes groans, eeps, or cackles.
- Super-Persistent Predator: He will always attempt to eat Marina, no matter what would happen if he fails.
- Villain Protagonist: The main protagonist of the show who tries to eat Marina.
- Weak, but Skilled: He is unable to beat Sharko, but he and Bernie are both really great builders and constructors.
- Would Hit a Girl: Zig has no problem with devouring Marina.
Bernie the Hermit Crab
- A Lizard Named "Liz": A bernard-l'hermitenote named Bernie.
- Cute Is Evil: In a way. Bernie helps Zig hunt down Marina, as he sees it just as another animal-eats-animal thing.
- Hypercompetent Sidekick: Zig's sidekick, who is more skilled and smarter than Zig.
- Minion with an F in Evil: He usually doesn't mind Sharko and Marina being around and would rather do his own thing.
Marina the Mermaid
- Bare Your Midriff: She wears a strapless bikini.
- Beware the Nice Ones: She can be pretty aggressive when she's upset.
- Brainless Beauty: She's not the sharpest tool in the shed, considering she never seems to realize when Zig's trying to eat her.
- Cute, but Cacophonic: In Season 2, it is revealed in some episodes that she is able to scream loud enough to blow anyone away.
- Dark-Skinned Redhead: She has red hair, tan skin, and a green tail.
- Friend to All Living Things: Pretty much all sea creatures love her.
- Genki Girl: Marina is very playful.
- Half-Human Hybrid: Her father is a human sailor.
- Huge Guy, Tiny Girl: She is friends with a giant shark.
- Interspecies Romance: She is a mermaid and Sharko is a shark.
- Manchild: She's an adult, but acts like a giddy little girl most of the time.
- Ms. Fanservice: Is the main source of fanservice on the show, on account of being a curvaceous mermaid who shows some skin.
- Nice Girl: She's generally the nicest character on the show and likes almost everyone she meets. Then again, that's not saying much.
- Our Mermaids Are Different: She can walk on her tail fins. She's also half-human.
- Prone to Tears: Marina is sometimes prone to bawling her eyes out when something makes her upset, such as in "Nurse Marina", where she realized she couldn't care for Zig if he felt better, and "Volcano Turbo", where her starfish stack gets destroyed twice in a row.
- Squee!: She tends to do this often when excited or happy about something. Most noticeable when she sees Zig disguised as Santa.
Sharko the Shark
- Anti-Hero: While he's heroic, he appears to like hurting Zig.
- Bruiser with a Soft Center: He has a huge soft side for Marina.
- Department of Redundancy Department: His name is Sharko!
- Hero Antagonist: To Zig's Villain Protagonist.
- Huge Guy, Tiny Girl: He is friends with a small mermaid.
- Interspecies Romance: He is a shark and Marina is a mermaid.
- Jerk with a Heart of Gold: Sharko may enjoy injuring Zig and sometimes hurts him when he did nothing wrong, but he isn't so bad deep down.
- Lightning Bruiser: He possesses Super Strength, can move very fast, and is quite durable.
- A Lizard Named "Liz": A shark named Sharko.
- Threatening Shark: Averted with Marina, but played straight with Zig. Justified since Zig is often trying to eat Marina.
- Corrupt Corporate Executive: Shows up as a music producer in one episode, getting Marina to sign a contract that forces her to attent fan signings for far longer than she can handle.
- Jerkass: It is quite telling as he is one of the few characters Marina dislikes.
- Prince Charmless: He's the king of the ocean and a jerkass.
- Big Badass Rig: Can summon various objects made of water, including a huge truck.
- Continuity Error: He is Marina's father in Season 2, but in Season 1, it was revealed that Marina's father was a human sailor.
- Large Ham Entrance: Enters the scene on his throne carried by a tidal wave.
The Wizard of the Volcano
He is a wizard that lives in the volcano of the island, with a cold flame on the top of his head. He possesses many powers and artifacts. He appears only from the Second Season.
- Abhorrent Admirer: of Marina.
- Expy: of Hades, in the Disney version (see Hercules). He is more similar to a necromancer: no Reign of Deads.