The Three Investigators

1. Jupiter Jones, First Investigator - A former child actor, Jupiter is intelligent, stocky, and has a remarkable memory and deductive skills. Jupiter is an orphan who lives with Uncle Titus Jones and Aunt Mathilda, who run a salvage business. Jupiter is not exactly fit, and a bit plump. He goes by the nickname "Jupe." In Germany, Jupiter Jones is called Justus Jonas.
2. Pete Crenshaw, Second Investigator - Pete is an athletic youth who dislikes dangerous situations but is nonetheless reliable as the "action member" of the team. Pete loves and cares for animals. His father is a special effects man in Hollywood. In Germany, Pete Crenshaw is known as Peter Shaw.
3. Robert "Bob" Andrews, Records and Research - Bob is studious, meticulous, and wears glasses. Early in the series he wore leg braces because of an accident he had, relegating him to a more studious and less physical approach to investigation. Bob works in the local library part-time, suiting his role as data collector. His father is a newspaper man, and occasionally gives Bob helpful hints.

Supporting characters

1. Worthington - Worthington is a British chauffeur who drives the Three Investigators around in a Rolls Royce. As time passes, he also becomes a confidante and helper in the boys' investigations. In the German edition, Worthington has the name Morton.
2. Alfred Hitchcock - Hitchcock was the boys' first patron who "introduced" their first 30 cases. In truth, the introductions were written by each book's author, not by Hitchcock himself. Random House paid Hitchcock for the use of his name. After the death of the movie mogul in 1980, the Hitchcock estate asked for more money, and the publisher refused. The last Hitchcock book was The Secret of Shark Reef. From then on, the boys' cases were introduced by the (fictional) famous detective-turned-writer Hector Sebastian.
3. Hector Sebastian - Sebastian took over the patron role beginning with The Mystery of the Scar-Faced BeggarThe Secret of Terror Castle, which was "introduced" by the fictional Reginald Clarke, a movie producer. This was necessary since a movie producer (originally Hitchcock) was central to the plot, and Hector Sebastian did not fill that role. (#31). Hitchcock's name and silhouette on the cover art of each book were then replaced by a stylized keyhole. Later, all of the Hitchcock volumes were reprinted with the keyhole and introductions by Hector Sebastian. The one exception was the reprint of the first story,

Recurring adversaries