Sylvester has a short auburn hair with two single short curly fringes in each side of his head, his nose resembles a carrot and black eyes. He also wears his small eyeglasses.
His primary appearance, is a classic 1910's dark green formal suit jacket with a matching green formal vest in a white long sleeve button shirt with a red neck tie on the collar, dark green pants and black shoes.
As his alter-ego The Hooded Claw, Sylvester's formal suit is now purple and dressed in a very long green collared cloak and black shoes. He also wears a purple mask and a matching green baggy hat with black linings on his head.
Before he wears his disguised form, Sylvester is seen in both the opening and one of its episodes where Penelope left for her travels, he has brought his hooded claw costume and his hat in his left hand as he completely wears it to do his plans to kill Penelope by setting some traps for her.
Relationship with Penelope Pitstop
His character is really (and physically) Penelope Pitstop's guardian and love interest, Sylvester Sneekly, in disguise. His main goal in the series is to do away with Penelope so he can take her fortune for himself in 1914.
In the episode "Big Top Trap", he actually reveals that he's Sylvester Sneekly (the Hooded Claw) to Penelope, but she doesn't believe him, thus still leaving her in the dark.
At the end of each episode, the Hooded Claw always vows to the viewers and the narrator that the next time, he would finally get rid of Penelope and take her fortune.
When he fails to get rid of Penelope as she was rescued by The Ant Hill Mob or being outsmarted by Penelope who manages to escape from his traps, his catchphrase is "Blast!".
Interference by the Ant Hill Mob and Chuggaboom
He has also made attempts to get rid of The Ant Hill Mob because of their constant interference with his plans to kill Penelope. He often refers to them as "little pests", "ragamuffins" and "those pint sized pests". Sometimes, he would use attempt to get rid of them, like trying to stop them by giving them odd liquids to drink, tickling http://hanna-barbera.wikia.com/wiki/Chugga-Boom, or trapping them. (used to be called, http://hanna-barbera.wikia.com/wiki/The_Bulletproof_Bomb)
The Bully Brothers
The Hooded Claw has two minions, the Bully Brothers, who are the only visible characters who know that Sylvester Sneekly is, in fact, the Hooded Claw. The Bully Brothers would normally do whatever he told them to do. However, there have been occasions in which the Bully Brothers would ask if they could do something else, such as "We want to go to Coney Island" or "While we're here, may we look for acorns?" Comments such as these would annoy the Hooded Claw and he'd threaten them, which would always get the brothers back to helping him get rid of Penelope.
The Narrator's Interference
Whenever the narrator (who also knows that the Hooded Claw is Sylvester Sneekly) would verbally interfere with the Hooded Claw's plans, the fiend would usually try to look down upon him by calling him "wise guy", "a busybody" and "nosy", thus breaking the fourth wall.
Disguises and Perils
The Hooded Claw is a master of disguise's, (which he mostly uses to lure Penelope into another of his traps). At first, Penelope always has no idea that it's the Hooded Claw until he reveals himself to her. His disguise's include Penelope herself, Clyde of the Ant Hill Mob, one of Chugga-boom's spare tires, an abominable snowman, a lumberjack, a lumber tycoon, the Earl of Crumpet and a Chinese detective.
The Hooded Claw's perils are complex, clever and secure (some are described by the Claw as "doozies"). However, Penelope is always able to escape from them, using her intellect and special talents. Her escapes frustrate him and force him to put her into another peril.
In the final episode, "London Town Treachery" he disguises himself as the Earl of Crumpet in which Penelope wants to return the painting to its owner. He disguises this so that he can capture Penelope for his plans to get rid of her. When the Ant Hill Mob are transformed into Hydes thanks to his own plans for making them drink an odd juice. The Hooded Claw became dismayed by his own actions after the Hyde version of the Ant Hill Mob has the same motives as he is to get rid of Penelope. By the time, their trap is set in motion by igniting a rocket at the roof of the cage which Penelope is inside as it ignites into the ocean which Penelope manage to escape the cage by using a saw fish before she will be eaten by a sea monster. As the Ant Hill Mob eternally returns to their normal selves they helped Penelope to get through the shore. The Hooded Claw eventually catches her as he make another peril one last time. At the London Tower, Penelope is tied in a clock's hand as The Hooded Claw explains about the trap he set up which Penelope will fall as the hand will struck on the sixth and lands in the trampoline and lands to pull the trigger of the dynamite plungers that will set the London Bridge fall. When the Ant Hill Mob are on their way to rescue Penelope, the clocks hand had struck in the sixth causing Penelope to fall into the trampoline. But the Ant Hill Mob manage to catch her in time foiling the Hooded Claw's plans. In the end of the episode, Penelope returns the painting to the real Earl of Crumpet as the Ant Hill Mob is on her side as an explosion can be heard. It reveals that The Hooded Claw got slipped and landed on the dynamite plunger and was exploded from his own trap as the bridge debris had landed on top of him. He warns the narrator that next time he vows to capture Penelope and he will make various traps to get rid of her and gets her fortune as he makes his last evil laugh as his brow had raised finally shows his evil motives.
- "I'll get you, Penelope Pitstop!"