Formal:
* Mentor: Emphasizes guidance and personal development.
* Trainer: Focuses on skill development and instruction.
* Instructor: Similar to trainer, but can encompass a broader range of subjects.
* Tutor: Specifically for academic subjects.
* Facilitator: Guides a group towards a goal.
* Leader: Emphasizes direction and motivation.
* Supervisor: Focuses on oversight and performance management.
Informal:
* Teacher: Broadly used, but can be more casual.
* Guide: Emphasizes direction and support.
* Advisor: Provides counsel and advice.
* Guru: Implies expertise and authority.
* Boss: Informal, can be used for anyone in a leadership role.
Sports:
* Manager: Oversees a team's operations.
* Skipper: Used for captains in some sports.
* Trainer: Focuses on physical conditioning.
* Strategist: Emphasizes game planning.
The best word will depend on the specific context and the role of the person you're referring to.