Hero

A hero willingly sacrifices their needs for others. They are actively learning and doing, and undergo transformation. They are flawed beings that have universal qualities. 

Mentor

A teacher or trainer who aids the hero by teaching and protecting them. The mentor motivates the hero to overcome their fears and also prepares them for the journey.

Threshold Guardian

A character who serves to keep the unworthy from entering. They cluster around thresholds, and can be overcome by being passed or made into an ally. These guardians serve to test the hero's character and commitment to the journey.

Herald

A character (or item) that issues challenges and announces coming change. Heralds serve to motivate the hero into action. 

Shadow

This aspect represents the "dark side;" villains, antagonists, and enemies. These characters often do not think of themselves as villains and serve to challenge the hero. By being a worthy opponent they create conflict to bring out the hero's best. 

Trickster

The embodiment of mischief, this character desires to create change. They serve to ground the hero by pointing out their follies and serve as comic relief. Tricksters are frequently a catalyst who causes healthy transformations. 

Shapeshifter

A shifting or unstable character, often of the opposite sex. They mislead the hero and act as a catalyst of change by bringing in doubt and suspense. 

Hero

Jonathon Thomas Merriweather, or Jon-Tom, is brought to the special world by a turtle known as Wizard Clothahump. On Earth, Jon is a law student who play guitar and spends his time stoned. In the new special world, he discovers he is a spell singer, or a mage who casts spells through playing songs. Using this power, he sets out on a series of adventures that range across this special world as well as his own. 

-- The Spellsinger series, Alan Dean Foster

Mentor

Dallben is the iconic image of the mentor-- an ancient wise man with a long white beard. He is the protector of Hen Wen, an oracular pig, and holder of the Book of Three. As guardian of Taran, he offers the boy guidance and advice along his journeys. 

-- The Prydain Chronicles, Lloyd Alexander 

Threshold Guardian

Inigo Montoya and Fezzik initially are threshold guardians who serve to keep Wesley away from Buttercup, whom they have kidnapped. By defeating them, he gains their loyalty and aid later during the Ordeal. 

-- The Princess Bride, William Goldman

Herald

Dobby the Elf's initial appearance serves to bring Harry back to the wizarding world-- despite his warning that Harry must not go back to Hogwarts. He also alerts him to the opening of the chamber of secrets, and the continued battle with the previously introduced villain, Voldemort. 

-- The Chamber of Secrets, J.K. Rawlings

Shadow

Mrs. Coulter serves her church by doing their dirty work. She kidnaps children and amputates their daemons to further experiments being endorsed by the church. Her faith is so strong that she is even willing to do so to her own daughter, placing her in danger. In the end, however, she realizes her love for Lyra and tries to protect her. 

-- His Dark Materials, Phillip Pullman

Trickster

Prince Kheldar, better known as Silk, is a spy who is known to be dishonest. Despite his colorful character, he aids Garion throughout the Belgariad epics, becoming a close ally. 

-- The Belgariad, David Eddings

Shape shifter

The Unicorn herself is the shape shifter throughout her adventure. Part of her magic is her innocence, and much of the time her own physical form influences her thought processes, terrifying her. 

-- The Last Unicorn, Peter S. Beagle