Characters in The Secret of Skull Mountain

Frank Hardy

Also in Crawling with Zombies, Deadly Strategy, Time Bomb, At All Costs, Break-Up!, Deception on the Set, A Figure in Hiding, The Twisted Claw, Showdown at Widow Creek, The Disappearing Floor

Joe Hardy

Also in Crawling with Zombies, Deadly Strategy, Time Bomb, At All Costs, Break-Up!, Deception on the Set, A Figure in Hiding, The Twisted Claw, Showdown at Widow Creek, The Disappearing Floor

The Weird Hermit

The Crime Syndicate Gang

Fenton Hardy

Also in The Twisted Claw, The Clue of the Broken Blade, The Flickering Torch Mystery, The Secret Panel, The Blackwing Puzzle, Mystery of the Desert Giant, The Mystery of the Spiral Bridge, The Jungle Pyramid, The Firebird Rocket, The Crowning Terror