Frank Lucius Packard (February 2, 1877 - February 17, 1942) was a Canadian novelist born in Montreal, Quebec. He worked as a civil engineer on the Canadian Pacific Railway. He later wrote a series of mystery novels, the most famous of which featured a character called Jimmie Dale.

Jimmie Dale is a wealthy playboy by day, with a Harvard education and membership to New York City's ultra-exclusive private club St. James. But at night he puts on a costume and becomes The Grey Seal, who enters businesses or homes and cracks safes, always leaving a diamond shaped, grey paper "seal" behind to mark his conquest, but never taking anything. He was just doing it for "the sheer deviltry of it" at first, but when a woman catches him, she blackmails him to war on certain crime organizations.

Jimmie Dale/The Grey Seal is often credited with greatly influencing and popularizing later pulp and comic book heroes. The foppish playboy-by-day-crimefighter-by-night routine had a precursor in The Scarlet Pimpernel, but it was Jimmie Dale that brought the idea into a contemporary setting and added the idea of a costume and mask for his secret identity, serving as a possible influence for characters like Zorro and The Shadow. He also established the concept of a hero's secret hideout or lair, The Sanctuary, a precersor of the Batcave or the Fortress of Solitude. (Summary by Wikipedia and Maire Rhode)