The main characters in the movie are the same as in the book--the students who eventually become known as the "Freedom Writers" and their teacher, Erin Gruwell. "Mrs. G.", as they call her, is played by Hilary Swank. Other character roles include: Scott Glenn as Steve Gruwell, Imelda Staunton as Margaret Campbell, April Lee Hernandez as Eva Benitez, Mario as Andre Bryant, Kristin Herrera as Gloria Munez, Jaclyn Ngan as Sindy Ngor, Sergio Montalvo as Alejandro Santiago, Jason Finn as Marcus, Deance Wyatt as Jamal Hill, Vanetta Smith as Brandy Ross, Gabriel Chavarria as Tito, Hunter Parrish as Ben Daniels, Antonio Garcia as Miguel, and Giovannie Samuels as Victoria.
Check out the official website of the Freedom Writers ( http://www.freedomwriters.com/ ) for more information. I've also included a link to books by Erin Gruwell and the Freedom Writers.
The main characters in "Freedom Writers" are the teacher, Erin Gruwell, and the students.
Some of the students play more prominent parts in the movie than others - for example, Eva, the most vocally rebellious student in the class; Jamal, who is the target for racist comments; Cindy, whose boyfriend is shot by Eva's gang; and Ben, who is the only white kid in the class and is scared of everyone. Scott, Erin's husband and Miss Campbell, the administrator of the school, are also important characters, though I wouldn't consider them the main ones.
The movie also includes many characters who are not named as well as less prominent characters such as classroom visitors and other school staff.