Gloria is a hippopotamus who resided in the Central Park Zoo as an attraction. She is good friends with Alex, Marty, and Melman. She is the tritagonist of the film series and the sole female of the quartet. Like everything hippo, Gloria is fat, her skin is gray, but in the belly is a little lighter than the rest of the body. Her huge belly caused many problems, such as Madagascar 3: Europe's Most Wanted where she stayed stuck in the pipe, or when she destroyed the glass and she and her friends fell to the casino.
As a hippopotamus, Gloria had a passive nature when it came to most problems, and served as the voice of reason for her friends. At the time of Marty the zebra's birthday, Gloria is another animal in the Central Park Zoo and was one of the many attractions, drawing crowds that enjoyed seeing her swim about in her water tank. She would also receive the star treatment as one of the zoo's main attractions and attend Marty’s birthday party. At this party, Marty announced his wish upon blowing out the candles on his cake: to go to the wild. Gloria, Alex and Melman tried to have Marty come to his senses by telling him that life out in the wilds was savage and difficult, whereas life in the zoos was adequate. Marty was unhappy at hearing this and Gloria told Alex to go and console Marty. Later that night, however, Marty acted out his wish and headed straight for the Terminal Station so as to take a train and go to Connecticut, where Marty heard that wide open spaces were found. Gloria urged both Alex and Melman to come with her so as to find Marty and bring him back before any people would notice. They were found, regardless, alongside Mason and Phil, the two chimps; and a troupe of secretive penguins, all ending up tranquilized with darts.
When they all came to, they found themselves in crates bound for Africa. When the penguins hijack the ship, the crates fall into the ocean and wash up on the island of Madagascar. After some confusion, they start to set up their own society and attract the attention of a lemur colony.
Gloria is happy to help her friends save Christmas, and shows her usual amount of enthusiasm throughout the special, even when helping Melman out of various situations.
It is also shown (perhaps guessed) that she loves children, as when the girl named Abby hugs her friends, and then her, Gloria hugs her back.
In Madagascar: Escape 2 Africa, Gloria is first seen as a young hippo along with Marty and Melman looking over at Alex, who had just arrived at the zoo. She says that Alex looks cute, much to Melmans, who has feelings for her, dismay. She expresses a desire to join in the zoo breeding program, in the hopes of finding a boyfriend. When the animals crash land in Africa, she attracts the attention of a hippo named Moto Moto ("Hot Hot" in English). Though she thinks he is the ideal boyfriend at first, she realizes that he only loves her because she is fat, where Melman loves her for who she is. Realizing that she loves Melman back, she convinces him not to sacrifice himself into the volcano and Gloria grabs him by the horn and says, "It's crazy to think that I had to go half way around the world to find the perfect guy was right next door..." and then joins the other animals in rescuing Alex from Nana. In the end of the film, Gloria ends up starting a relationship with Melman.
It's her first Valentine's Day with Melman and as such she's quite excited but when she wants to spend time with him, he's busy planning a surprise for her. During the day Gloria has many questions on her mind like if Melman is avoiding her and wondering where he is. When she spots him, Gloria thinks he's dumping her on Valentine's day. But later, she finds his list of things for her surprise and tells him that all she wanted to know that he was thinking about her.
Gloria never really expected to fall in love with her best friend, Melman, but now that she has, she could never really see it any other way, and when the group decides that they've waited long enough and it's time to go and find the penguins Gloria is happy to go, as long as he comes too. When they reach Monte Carlo, the group runs into misfortune when they are spotted in the casino and are pursued by animal control. The group ends up hiding with Circus Zaragoza in order to stay out of the way of the law. They find out that this circus, if it puts on a good enough show in London, will earn a contract for an American tour, which means a stop in New York City. Gloria and her friends immediately begin fine-tuning the show in order to ensure that they get the contract. This includes coming up with new acts for the show. Gloria decides that it would be a blast to do a dancing routine with Melman, only to find that he is unsure of himself in regards to his dancing abilities. It takes a pep-talk and a lesson on top of a tightrope for the couple to find their routine, dancing while on the tightrope! This act is one of several the ends up getting the circus the contract. When they finally reach New York City however, Gloria finds that the zoo is not exactly what she remembered, she's especially unhappy to find that there is a big wall in between her and Melman's enclosures. The zoosters decide that a better life would be had if they join the circus. Gloria and Melman are only too happy to join the show permanently, it's way better than having to talk to each other through a wall all the time.