Zig & Sharko

• Zig – an anthropomorphic brown hyena who is currently 18 years old, came to the island as a baby from Africa and was adopted by a female gorilla. He is best friends and adoptive brothers with Bernie, since his childhood, and frequently plots to capture Marina to eat her, but is foiled in the process by Sharko. His schemes that he concocts for this purpose are often elaborate but never truly succeed. The character's behavior and characteristics were in part inspired by Wile E. Coyote.
• Sharko – an anthropomorphic great white shark, the age of 20, who loves Marina and often does everything to protect her from Zig's schemes, as well as anyone else who seeks to harm her. He is often portrayed as muscular and athletic (a recurring element is the character's constant flexing of muscles that aren't generally shown), is a fan of table tennis, and is capable of walking on land (as do all the animated series' aquatic characters) without issue. Although his devotion to Marina is out of loyalty and love, he sometimes occasionally causes trouble himself and often is punished for it.
• Marina – a mermaid, who is good-natured but quite naive. She maintains a positive relationship with everyone, including Zig because of being unaware of his intentions and thus not being afraid of him. She is often portrayed as wearing a small sea star as a decoration in her hair, possessing a smartphone, and capable of walking on land by using the flippers on her tail as feet. She is often intrigued and interested in new things such as farming, skiing, and other activities and hobbies, and often attempts them usually with Sharko offering to help arrange it. She often enjoys singing, though Sharko dislikes it. She was inspired by Ariel from The Little Mermaid.
• Bernie – a red anthropomorphic hermit crab, and Zig's best friend and adoptive brother since childhood. He often collaborates in Zig's schemes to capture Marina, though in reality holds no grudge against her or Sharko. He is often denoted as being quite smart, and capable of coming to the rescue when needed.

Alongside the main characters, various episodes feature a variety of background and minor characters to the stories - jungle animals, aquatic lifeforms, and various human characters - in the first season, one of these human characters is portrayed as a Japanese cargo ship captain, who, as a running gag, frequently crashes his ship into the island and is forced to return home via a rubber dingy. Throughout the first season, several episodes featured the supporting character of Neptune, based on the mythological Roman god of the sea and portrayed as a vain, muscular merman with numerous killer whale henchmen, who competed with Sharko for Marina's love, despite her disliking him whom Marina despises and often has to rely on Sharko and Zig to keep him at bay, the production team also added in the Greek god Hades, portrayed as a muscular, elder merman, who served as Marina's adopted father, and an amnesiac human cargo plane pilot who often exhibits the behavior of a monkey due to his condition.

Throughout the first season, much of the plots revolve around the oceans surrounding a tropical volcanic island, alongside its coastline, in which Marina often spends the day residing on a rocky pinnacle off the coast during the day, while residing in an underwater home that she shares with Sharko. In the second season, the plots shifted to the island itself, including its beaches, volcano, and jungle, with some changes for the main characters - Marina takes residence in an ornate, life-sized sandcastle evocative of the Taj Mahal, built by Sharko; Zig and Bernie live with the cargo plane pilot in his crash plane within the jungle, and Sharko operates as a lifeguard for the aquatic lifeforms who frequent the beaches. In the third season, the main characters and the island's inhabitants move onto a cruise ship to travel the oceans, where much of the season's plots take place.