Jimmie Dale is a fictional character created by Frank L. Packard in 1914.
He was a wealthy playboy by day, but at night put on a costume and became The Gray Seal, who enters businesses or homes and cracks safes, always leaving a diamond shaped, gray 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.
Dale's adventures first appeared in People's Magazine and then were collected into novels: The Adventures of Jimmie Dale (1917), The Further Adventures of Jimmie Dale (1919), Jimmie Dale and the Phantom Clue (1922), Jimmie Dale and the Blue Envelope Murder (1930), and Jimmie Dale and the Missing Hour (1935), with the serializations generally appearing the year before the novel version was published.
In 2007, the first two books featuring Jimmie Dale/The Gray Seal were re-released as an e-book entitled Return of The Gray Seal.
He also appeared in a movie serial, Jimmie Dale Alias the Gray Seal, in 1917.
Chapters titles were: 1. The Grey Seal 2. The Stolen Rubies 3. The Counterfeit Five 4. The Metzer Murder Mystery 5. A Fight for Honor 6. Below the Deadline 7. The Devil's Work 8. The Underdog 9. The Alibi 10. Two Crooks and a Knave 11. A Rogue's Defeat 12. The Man Higher Up 13. Good for Evil 14. A Sheep Among Wolves 15. The Tapped Wires 16. The Victory.
Jimmie Dale/The Gray Seal is often credited with popularizing and evolving what would greatly influence 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.
(This entry incorporates some material from Jess Nevins Encyclopedia of Pulp Heroes)