- LeVar Burton (Since 2005)
- Keith David
- Neil deGrasse Tyson
- Patrick Stewart
- Kelsey Grammer
- Liam Neeson
- Tim Allen
- Harrison Ford
- Tom Selleck
- Jeff Bridges
- Sam Elliott
- Kelsey Grammer
- Morgan Freeman
- Diane Sawyer
- Katie Couric
- Ann Curry
- Christiane Amanpour
- Lisa Ling
- Jane Goodall
- Sylvia Earle
- Robert Ballard
- James Cameron
- Elon Musk
- Sundar Pichai