Personality
Scooby-Doo and Shaggy share several personality traits, mostly being scared easily, but their friends (Velma Dinkley, Daphne Blake and Fred Jones) encourage them to go after the costumed villains usually with "Scooby Snacks", a biscuit-like dog treat or cookie snack (usually shaped like a bone or as shown in later versions of the cartoons Scooby's dog tag), though occasionally appealing to Scooby-Doo inherent loyalty and courage to take a more heroic stance.
In all iterations, Scooby has a speech impediment and tends to pronounce most words as if they begin with an "R", though most of the characters are able to understand him perfectly. His catch phrase, usually howled at the end of every mystery, is "Scooby-Dooby-Doo!" or "Rooby-Rooby-Roo", sometimes followed by a quirky chuckle.
When he solves cases with his nephew Scrappy-Doo, he's very protective of him, as he often runs after him to prevent him from going straight to the monster or ghost.