Monsters Inc - The Archetype Hero's Journey

The Hero:

Sully - A scarer who is close to breaking the all-time scare record

The Mentor:

Waternoose - Trained Sully at scaring.

The Herald:

Celia Mae - Announces when Sully has beaten the all-time scare record.

The Shadow:

Randall - Sully's rival for the all-time scare record, who is also behind a scheme to kidnap children.

The Threshold Guardian:

Roz - In charge of which doors Sully goes through, and is also in charge of the organisation stopping him from looking after Boo.

The Trickster:

Boo - A human child who accidentally follows Sully into the monster world and is the cause of all the problems following.

The Shapeshifter:

Waternoose - The CEO of Monsters Inc. who trained Sully but later turns out to be working with Randall trying to kidnap children.

Allies:

Mike - Sully's assistant who is with him throughout his entire journey.
The Abominable Snowman - He helps Sully and Mike when they get banished from the Monster world.