To find the "main characters" of the season, I went with the castaways who had the top 50% of confessionals in the season. For example, let's say Eric has 20% of the confessionals, then Sally has the next most with 15%, and Rufus has 10%, and LeBron has the fourth most with 5%, that adds up to 50, meaning Eric, Sally, Rufus, and LeBron are the "main characters" of the season.
Borneo
Richard Hatch
Kelly Wiglesworth
Susan Hawk
Sean Kenniff
Gervase Peterson
Australian Outback
Colby Donaldson
Keith Famie
Tina Wesson
Jerri Manthey
Africa
Lex van den Berghe
Ethan Zohn
Tom Buchanan
Frank Garrison
Marquesas
Kathy Vavrick-O'Brien
Sean Rector
Paschal English
Neleh Dennis
Vecepia Towery
Thailand
Helen Glover
Clay Jordan
Brian Heidik
Ted Rogers, Jr.
Jake Billingsley
The Amazon
Rob Cesternino
Jenna Morasca
Matthew von Ertfelda
Deena Bennett
Pearl Islands
Rupert Boneham
Jonny Fairplay
Sandra Diaz-Twine
Lillian Morris
Andrew Savage
All Stars
Rob Mariano
Rupert Boneham
Amber Brkich
Jenna Lewis
Tom Buchanan
Vanuatu
Chris Daugherty
Eliza Orlins
Twila Tanner
Ami Cusack
Sarge Masters
Palau
Stephenie LaGrossa
Tom Westman
Ian Rosenberger
Katie Gallagher
Bobby Jon Drinkard
Samoa because of Natalie