A list of the ancestors who were the "Companions" of William the Conqueror. A list of all of his proven companions is at Wikipedia: https://en.wikipedia.org/wiki/Companions_of_William_the_Conqueror

Beaumont, Robert de Sir, Count of Meulan  b. abt. 1049, d. 5 Jun 1118
Giffard, Walter II, 1st Earl of Buckingham  b. abt. 1015, d. 15 Jul 1102
Gilbert, Richard Fitz  b. bt 1030 - 1035, d. 1090
Grandmesnil, Hugh de  d. 22 Feb 1098
l'Aigle, Engenulf de  d. 17 Oct 1066
Toeni, Ralph III  b. bt 1025 - 1030, d. 24 Mar 1101/2