Character from Percy Jackson by Rick Riordan
The world's only friendly hellhound — she's the size of a tank, shadow-travels, and plays fetch with telephone poles. Daedalus gave her to Percy.
Mrs. O'Leary was Daedalus's pet hellhound, and when Daedalus died, she became Percy's. She's the size of a garbage truck, with red eyes that glow like coals and fur that drinks in the light. She can shadow-travel (teleport through darkness), which makes her the most effective transport in the demigod world. She also plays with boulders like tennis balls, knocks over small buildings by wagging her tail, and licks Percy with a tongue the size of a surfboard. She's a monster by species and a golden retriever by temperament, and she loves belly rubs that create small earthquakes.
An enormous black mastiff the size of a garbage truck, with red eyes and fur like shadow. She looks terrifying. She acts like a golden retriever who happens to weigh several tons.
Also known as: Mrs. O'Leary