- “I didn't make it all the way to third grade for nothing.”
- ―Percival McLeach[src]
Little is known about McLeach's background. He had three years of formal education before either being needed at home, quitting, or being expelled. He considers this a great achievement. It is unknown how he came by his pet goanna, Joanna, but while he accepts her help in his poaching endeavors, he constantly perceives her as incompetent and shows her little patience. At an unknown point, he captured several animals, including a frill-necked lizard named Frank and a koala bear named Krebbs, for profit and held them all in the same room for an unknown period of time prior to appearing in the film. Krebbs found it surprising that McLeach would add a human to his collection.
McLeach is an evil and eccentric poacher who captures rare animals and sells them, usually for their hides. Truly cruel, he clearly enjoys killing animals, at one point even singing a twisted version of the song "Home on the Range", and as evidenced by his deliberately missing Cody when about to feed him to saltwater crocs for real, is shown to be sadistic enough to toy with his victims before killing them. He is an excellent hunter and tracker, and despite only having a third grade education, he is very intelligent, cunning, able to lie and cheat effectively, also tossing Cody's backpack into the water so that he will be presumed to have been eaten by crocodiles, coming up with the plot to trick him into leading him to the eagle, and being aware that Cody will never believe he is just letting him go out of the 'goodness of his heart', maintains a nasty demeanor even as he releases him. He is also shown to be completely aware of the animals being sapient, as evidenced by his outright issuing orders to a then-escaped Frank the Frilled Lizard to get back to his cage, as well as being implied by his showing himself to anticipate the threat the mice played against him and even anticipating the eagle's intellect. He appears to be perfectly fine with up and out slaughtering Cody, as shown in the epilog and his plots to snuff out information from him. Despite all his negative traits, he is rather plucky and appears to have a decent sense of humor, making grim jokes and comedic movements, not to mention singing at odd points.
He has, for some reason, chosen not to kill Joanna, and although he beats or threatens her on several occasions, it is always when she misbehaves or does something stupid. Despite this, he occasionally praises or makes jokes with her, and on one occasion, he even caresses her. However, it is heavily implied that he generally abuses her. He drives a modified Half-track truck with a cage and crane on the bed for capturing animals and a massive makeshift ram bar. He uses this truck for long travels and hunting. He uses the trucks crane to get rid of Cody but is halted when Bernard shuts off the truck and hides the keys. It is unclear what happens to the truck after McLeach's demise. It's possible that is was either repossessed or never recovered. Unable to find his truck keys he resort to using his shotgun to cut the rope.
At first glance, he does not appear healthy. He seems to be balding, sports a potbelly and is tall and quite lanky despite the grueling nature of his job. However, he is actually quite strong, able to fight off several saltwater crocodiles, which are considered among the most dangerous animals in the world.
He is dressed like an Australian stockman. He wears a brown Akubra hat with white crocodile teeth with its dark brown leather band decorated with a rare golden eagle feather. Around his neck is a dark gray backward facing bandanna. He wears a brown vest over his cream shirt. As seen, from capturing Marahute to trying to feed Cody to the crocodiles in Croc Falls, he wears a drizabone riding jacket but he took it off moments before falling into the river.
He is first seen on a wanted poster. His first on-screen appearance is him approaching one of the traps he has set, only to be surprised by having caught Cody. At first, he tries to persuade him that he's not a poacher, and seems prepared to let him go, but then realizes he knows the location of the great golden eagle Marahute. McLeach admits that he is a poacher, and has already caught the father. When Cody refuses to divulge the eagle's whereabouts, McLeach tosses his backpack to the crocodiles to trick the authorities into thinking Cody was eaten and kidnaps him.
At first, he tries to persuade Cody to reveal the location, offering him a 50/50 split. However, Cody continues to refuse his deals, and he contemplates torture. When Joanna steals his eggs, he is inspired to tell Cody the rumor that Marahute is dead, and that there's no point to keeping him, then mentions casually that her eggs will go cold without her. McLeach then follows Cody to the location of her nest and successfully captures her. Cody tries to save her but is recaptured by McLeach.
McLeach then attempts to kill Cody to tie up loose ends by feeding him to some crocodiles, but Bernard manages to stop the machine McLeach was using to lower Cody into the river. Then, McLeach responded by getting out of the vehicle and personally started firing at the rope holding Cody with a shotgun but is knocked into the river by Joanna, who was chasing Bernard. There, the crocodiles turn their attention from Cody to McLeach and attack both him and Joanna. He successfully fights them off, not realizing the huge waterfall behind him. Joanna makes it to shore and waves goodbye to him just as he realizes his predicament. He tries to escape, but the current sweeps him over the waterfall to his death.
McLeach and Joanna appeared in only one episode House of Crime where he is seen arguing with Stromboli. Later in the same episode, Percival was imprisoned with other Disney Villains as suspects of the mysterious disappearances, but he and the others were then suddenly kidnapped by the actual culprit.
- During the "Home on the Range" song, his singing voice was not provided by George C. Scott. Instead, it was provided by Frank Welker, who also voiced Joanna.
- When he first appears, he pulls a feather out of Cody's shirt and puts it on his hat, but in previous shots, there was already one there.
- His shotgun is a Winchester Model 1912 but with heavy modifications, such as a scope. One weird fact is when he first appears, it has two barrels. However, when he tries to shoot the rope holding Cody over the crocodile-infested waters, it only has one but still has a scope.
- Bryan Brown, Clint Eastwood, Paul Hogan, John Mahoney, Jack Palance, and Mandy Patinkin were all considered for the role of McLeach.
- He is similar to his predecessor, Madame Medusa. They both kidnap a little child to get an item they want to become rich. They both have vicious pets. Both have shotguns. And they both end up being chased by crocodiles in the climax of each movie.
- Ironically, George C. Scott was actually an animal lover.
- Due to his willingness to kill Cody, he is one of the darkest Disney villains and is even more evil than Medusa.