Suggestions by @autumnblack

Joe Alwyn

as Phil Latham in A Separate Peace

Young Christian Bale

as Brinker Hadley in A Separate Peace

Hugh Jackman

as Mr. Prud'homme in A Separate Peace

Dane DeHaan

as Elwin Lepellier in A Separate Peace

Young Leonardo Dicaprio

as Phineas in A Separate Peace

Leonardo DiCaprio

as Phineas in A Separate Peace