who can name them all and the approximate years they were on?

Steve Allen-1950 or 51 to 1956 (I think)

Jack Parr-1956 to 1962

Johnny Carson-1962 to 1992

Jay Leno-1992 to 2009

Conan O'Brian-2009 to 2009

Jay Leno-2009 to Feb. 2014 when he'll step down & Jimmy Fallon will replace him.