I have definite reservations about the continuing survival of this category. As others have pointed out, it effectively creates a "ghetto" for youthful actors. That said, a few additional winners, some of whom have been overlooked:
1968: Mark Lester, Oliver!
1971: Peter Ostrum, Willy Wonka and the Chocolate Factory
1973: Tatum O'Neal, Paper Moon (who won Best Supporting Actress for the role IOTL).
1977: Cary Guffey, Close Encounters of the Third Kind (who would become the youngest-ever Oscar recipient, ahead of Shirley Temple).
1979: Justin Henry, Kramer vs. Kramer
1980: Danny Lloyd, The Shining
1982: Henry Thomas, E.T.: The Extra-Terrestrial (He definitely would have won over Drew Barrymore. He was the star!)
1984: Molly Ringwald, Sixteen Candles
1985: Sean Astin, The Goonies
1986: Corey Haim, Lucas
1988: Winona Ryder, Beetlejuice
1990: Macaulay Culkin, Home Alone
1991: Christina Ricci, The Addams Family
1993: Anna Paquin, The Piano (Another OTL winner, for Best Supporting Actress.)
Those are the ones off the top of my head. Note that these are listed by award year, not the year in which the ceremony takes place.