A list of the ancestors who signed the Magna Charta. Most have entries in Wikipedia which you can find here: http://en.wikipedia.org/wiki/Category:Magna_Carta_barons

Bigod, Hugh le, 5th Earl of Norfolk  d. bef. 18 Feb 1224/25
Bigod, Roger le Sir, Knt., 4th Earl of Norfolk  b. bef. 1140, d. bef. 2 Aug 1221
Bohun, Henry de, 5th Earl of Hereford  b. abt. 1175, d. 1 Jun 1220
d'Aubeney, William  b. aft. 1147, d. 7 May 1236
Huntingfield, William de Sir, Knt.  b. abt. 1160, d. bef. 25 Jan 1220/21
Lacy, John de  b. abt. 1192, d. 22 Jul 1240
Lanvalay, William de  b. aft. 1189, d. bef. 3 Oct 1217
Malet, William  b. bef. 1173, d. abt. 1216
Mowbray, William de Sir, Knt.  d. bef. 25 Mar 1224
Percy, Richard de Sir, Knt.  d. abt. Aug 1244
Robert, John Fitz  b. bef. 1191, d. bef. 20 Feb 1241
Roos, Robert de  b. abt. 1172, d. 1227
Say, Geoffrey de Sir, Knt.  b. abt. 1180, d. 19 Aug 1230
Vere, Robert de Sir, Knt., 3rd Earl of Oxford  b. aft. 1164, d. bef. 25 Oct 1221
Walter, Robert Fitz Sir, Knt.  b. say 1175, d. 9 Dec 1235