This is not about how good character they played but about how much they acted and looked like the book character.
http://www.ranker.com/list/best-book-to-movie-and-tv-casting/humbertoibarra,
Aidan Gillen
A Song of Ice and Fire series
Helena Bonham Carter
Harry Potter Series
Ian McKellen
Lord of the Rings series
Logan Lerman
Percy Jackson and the Olympians
Maggie Smith
Harry Potter series
Martin Freeman
Lord of the Rings series
Richard Harris
Harry Potter series
Robbie Coltrane
Harry Potter series
Viggo Mortensen
Lord of the Rings series
Noomi Rapace
The Girl with the Dragon Tattoo