In the anime Kimba the White Lion, the black leopard Cassius (Tott in the original Japanese and Sylvester in the 90s English redub) is the evil adviser of the recurring antagonist Claw.
Cassius appears as Claw's second-in-command and adviser, often devising the various plots set out to deal with Kimba. One episode revolves around a plot of turning several of Kimba's associates against him by appealing to their desire to eat meat again. He also forces some of Kimba's fellow youth to eat meat, thus leading them to turn against Kimba when they desire to eat their non-carnivore associates. For a time, he tricks Kimba and company into believing he's turning a new leaf along with Tom and Tab so as to enact Claw's plot to trap them in the amusement park/safe haven. Cassius enlists the Black Four to aid in this scheme, but they and he are defeated.
Cassius also has acted on his own on other occasions. During one episode, he forces an old owl Gypsy into creating a poisonous potion that Kimba is tricked into ingesting. Gypsy has a change of heart and aids Kimba, which results in her getting injured by Cassius. Nevertheless, he is defeated once more.
Like Claw, Cassius appears as a villain in the 1989 anime.
Toto acts as the semi-antagonist of the 2009 film, appearing for the first time without Claw or the hyenas. He is tragic figure - the last panther on earth. When he gives his final line at the end of the film, you have to feel it.
"I wasn’t meant to live in this world anyway. I’m a failed product, after all. Leo, I haven’t forgiven the humans. Ken’ichi, have our screams reached them at all? That’s all I needed. Thanks. This… is my way of leaving my mark."
Unlike Claw who is more apt to fly into a rage, Cassius is cool and calculating, capable of putting up a good show, such as when he tricks Kimba into believing he turned good. He is also shown as a bit of a henchmen wrangler, given his summoning of the Black Four with his whistle. But like Claw, he doesn't take kindly to the incompetence of his underlings and even angrily yells "GET!" at the Black Four when they perform their villain song.