Personality and design
Disney has long denied accusations that The Lion King is based on the anime series Kimba the White Lion, despite similarities between the names "Simba" and "Kimba", as well as some concept art depicting Simba as a white lion. The studio maintains that any parallels are coincidental. However, Broderick said he thought he had originally been cast in an American remake of Kimba because the characters seemed so similar to him at first. Because Disney was prioritizing Pocahontas over The Lion King, the former of which most of their experienced animators gravitated towards since the studio considered it the more promising of the two projects, Simba was one of the few Lion King characters animated at the studio's main California location. This proved challenging for the production team because Simba shares several scenes with characters who were animated in Florida.
The role of Simba's supervising animator was divided between Ruben A. Aquino and Mark Henn, the former of whom was the first animator hired for The Lion King. Henn served as the supervising animator of Simba as a cub, and Aquino animated him as an adult. Aquino and Henn worked on the character from Disney's California and Florida studios, respectively. According to Aquino, animating four-legged creatures is difficult because artists are required to draw twice as many legs as human characters, while still incorporating human-like qualities. For assistance, Aquino drew inspiration from Disney's previous animal films such as Bambi, Lady and the Tramp, and The Jungle Book. Aquino based his early drawings of Simba on Broderick, whose voice he said offers the character "a lot of humor and vulnerability ... which really gave me something to go on and made it easier for me to flesh out my performance". Aquino would quietly sketch Broderick live during his sessions, which would end up informing each other's performances. Because the adult version of the character is introduced mildly depressed, Aquino originally drew him with sad, soulful eyes and a disheveled mane, but redesigned him to look more heroic at Hahn's request. As a result, Simba ended up resembling Mufasa. To make sure the character looked believable, Aquino studied live lions loaned to the studio and consulted with zoologists.
Henn animated Simba's scenes from the beginning of the film until approximately the "Hakuna Matata" sequence, including Simba's first appearance as an adult towards the end of the musical number. Before The Lion King, his experience as a supervising animator was limited to predominantly female characters, having previously worked on Ariel from The Little Mermaid, Belle from Beauty and the Beast, and Jasmine from Aladdin. He initially campaigned heavily to animate the film's villain, Scar, because he wanted to do something different than the princesses he had become known for, but Hahn convinced him to work on Simba due to his experience with main characters. Hahn reminded Henn that the success of the entire film hinges on Simba's design, since he is considered the most important character in The Lion King, and the animator found it a welcome departure from leading ladies nonetheless. Aside from Andreas Deja who ultimately animated Scar, Henn was the most tenured animator on The Lion King, whose roster mostly consisted of newer or first-time animators. Simba proved to be a challenge because Henn was tasked with creating an animated character who would both appear and behave like a real lion cub for the first time. To achieve believability, Henn visited zoos, studied live lion cubs that were loaned to the studio for research, and consulted with wildlife professionals. Henn maintained that animators can not simply use their cats as reference models due to their different anatomies. Recalling their efforts to make his character as realistic as possible, Henn said that, unlike domestic cats, lion cubs “have a power ... underlying that seemingly soft exterior". He was also responsible for making sure Simba's appearance remained consistent between himself, the directors, and other animators.
When it came to animating the "I Just Can't Wait to Be King" musical sequence, Henn insisted that Simba remain on all-fours, despite the character exhibiting human characteristics by dancing. The animators would often observe and film the actors' recording sessions, using their mannerisms as visual reference, with Thomas proving particularly influential on Simba's design and personality. Henn described his version of the character as a young, cocky, inexperienced cub who had yet to mature, which he hoped would remind viewers of their younger selves. Compared to adult Simba, Simba is "looser" and less physically assured, which allowed Henn to draw him "a little more awkward, his feet were a little bigger, they could be a little floppier than when he's an adult". Although Henn and Aquino did not spend much time discussing the character's design with each other, both artists referenced live lions and received input from the same research team to determine how Simba should look and behave. Catherine Hinman of the Orlando Sentinel observed that the animators' extensive research resulted in "a lion cub who moves like his aristocratic cousins on the savannah but acts like the kid down the street". Tom Bancroft, an animator who worked on Simba under Henn, described his supervisor as the fastest animator at Disney at the time, making it difficult for other animators to acquire their own scenes to animate as Henn would typically do them himself. According to the Academy of Art University, Henn's work on Simba "further cemented his place in [animation] history".
Journalists reported that Simba's mane was based on how singer Jon Bon Jovi styled his hair during the 1980s. Simba spends 55% of his screen time as a cub, and the remaining 45% as an adult lion. At the time of the film's release, Simba had the most screen time of any Disney hero, appearing in 49.71% of the film (or 43 minutes and 51 seconds).
