Panther made his first appearance as the newest as well as the third member of the Star Wolf team in Star Fox: Assault, taking the place of both Pigma and Andrew. Panther is very conceited, egotistical and overconfident, which often embarrasses those around him, especially his teammates, Wolf, and Leon. He is also a coquettish flirt, and he considers himself a ladies' man. As a result, he attempts to flirt with Krystal several times, but she either ignores or outright rejects him, depending on the circumstances. (This, of course, changes, when they actually do wind up in a relationship during Star Fox Command, though the endings and possibly the game itself might be non-canon.)
His signature symbol is a red rose. This symbol is painted on the side of his Wolfen, making him the only pilot in the series to have any kind of marking on his ship, which distinguishes his Wolfen from those of his teammates. He uses it this marking to warn his enemies that he is coming to kill them. He also uses actual roses as his calling cards after killing victims with his own bare hands.
Super Smash Bros.
Panther appears in Super Smash Bros. Brawl as a trophy and two stickers: one based on his appearance in Star Fox: Assault (boosts tail attacks for Fox, Falco, and Wolf) and the other based on his appearance in Star Fox: Command (boosts energy attacks for any fighter). In Super Smash Bros. 4, Panther appears as a trophy in both versions and can be interacted with in the Lylat Cruise stage. In Super Smash Bros. Ultimate, Panther appears as a primary attack type spirit that can be battled against Wolf with increased speed.
In Star Fox: Command, Panther's surname is changed to Caruso, presumably due to translation error.
Similarly, the official website of Star Fox: Assault spelled his name as both Caroso and Caruso.
His surname in Japanese is closer to Caluroso, which is Spanish for "warm, hot, energetic, enthusiastic".
Panther seems to have a rivalry with three members in slightly different ways; he is a love rival to Fox, as the latter is already in a relationship with Krystal and she is the person Panther is smitten with. Panther also seems to exchange insults with Falco, and just as with every other Star Wolf member targeting each Star Fox member (Wolf to Fox, Leon to Falco, Pigma to Peppy, and Andrew to Slippy) Panther chases after Krystal.