Best Child Actors / Actresses Ever?

I have seen many modern films where the "child" roles seem so distant from any realistic portrayal of children. In the past, we had amazing child actors such as Margaret O'Brien, Natalie Wood, etc. I'm curious which child actors or actresses have stood out for you as being the most genuine portrayals of children on the silver / color screen. Some more recent believable were portrayed by Abigail Breslin and Brooklynn Prince. Any era is okay, although preferably movies before the 1960s.

Watched based on suggestions from this thread:

Secondhand Lions (Haley Joel Osment)

Other suggestions from this thread:

AI (Haley Joel Osment)

The Champ (Ricky Schroeder --1979).

Fly Away Home (Anna Paquin)

Interview with a Vampire (Kirsten Dunst -- 1994)

Poltergeist (Heather O'Rourke -- 1982)

E.T. (Henry Thomas -- 1982)

Kramer vs. Kramer (Justin Henry -- 1979)

Paper Moon (Tatum O'Neil)

Pay it Forward (Haley Joel Osment)

Taken (Dakkota Fanning)

The Explorers (Ethan Hawke)

The Railway Children (Jenny Agutter)

The Sixth Sense (Haley Joel Osment)

The Yearling (Claude Jarman)