Character interviews become especially valuable when the questions move beyond facts and force the character to reveal beliefs, contradictions, and vulnerabilities.
Here are categories:
Relationships

• Who do you love most?
• Who do you miss?
• Who annoys you?
• Who intimidates you?
• Who do you envy?
• Who do you wish understood you?
• Who would you call in an emergency?
• Who knows you better than anyone?
• Who do you blame for your current situation?
• If you could say one thing to someone in your life right now, what would it be?

Wants and Objectives

• What do you want right now?
• What do you think you want?
• What do you actually need?
• What are you trying to accomplish in this scene?
• What would success look like?
• What are you willing to do to get what you want?
• What line won't you cross?
• What's stopping you from getting what you want?

Fears

• What scares you the most?
• What are you avoiding?
• What would destroy you emotionally?
• What secret are you protecting?
• What are you afraid people will discover about you?
• What are you pretending doesn't bother you?

Personal History

• What is your first memory?
• What is your happiest memory?
• What is your most embarrassing memory?
• What is your greatest regret?
• What is the bravest thing you've ever done?
• What is the worst mistake you've ever made?
• When was the last time you cried?
• What event changed your life?

Opinions About Other Characters

• What do you really think of _____?
• What would you never say to _____'s face?
• What do you wish _____ understood?
• What do you admire about _____?
• What frustrates you about _____?
• If _____ disappeared tomorrow, how would your life change?

These are particularly useful in scene work.

Values and Beliefs

• What do you believe about love?
• What do you believe about success?
• What do you believe about family?
• What do you believe about friendship?
• What do you believe about honesty?
• What do you think makes someone a good person?
• What is worth fighting for?
• What is worth dying for?

Contradictions
These often produce the richest acting discoveries.

• What do you say you want?
• What do you secretly want?
• What do you pretend doesn't matter?
• What matters more than anything?
• What is something you criticize in others but do yourself?
• What truth are you avoiding?

Fun "Press Conference" Questions
Performers often enjoy these.

• What is your favorite food?
• What music do you listen to?
• What would your social media look like?
• What is your biggest pet peeve?
• What is your guilty pleasure?
• What's your dream vacation?
• What's something you're obsessed with?
• What would your search history reveal?

Scene-Specific Questions
Perfect immediately before rehearsal.

• Why are you here?
• Why today?
• Why now?
• Why not leave?
• Why not tell the truth?
• What happens if you fail?
• What do you hope the other person says?
• What answer are you afraid of hearing?

Deep-Dive Questions
For advanced actors or lead roles:

• What wound are you carrying?
• What are you trying to prove?
• What are you ashamed of?
• What do you need forgiveness for?
• What have you never forgiven?
• What are you still waiting for?
• When do you feel most alone?
• What do you hope people remember about you?

One variation that works exceptionally well with high school performers is the "No Time to Think" Interview:
The actor sits in the hot seat and must answer instantly, in character, with no pauses longer than two seconds. The speed prevents intellectualizing and often reveals surprisingly truthful, spontaneous discoveries about the character.