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  b. say 1186, d. 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. 1176, d. 1 Jun 1220
Clare, Gilbert de Sir, Knt.  b. abt. 1180, d. 25 Oct 1230
d'Aubeney, William  b. bt 1148 - 1168, d. 7 May 1236
Huntingfield, William de Sir, Knt.  b. abt. 1160, d. bef. 25 Jan 1220/21
Lacy, John de  b. abt. 1180, d. 22 Jul 1240
Lanvalay, William de  b. say 1190, d. bef. 19 Oct 1217
Malet, William  b. abt. 1175, d. bef. 1219
Mowbray, William de  d. bef. 25 Mar 1224
Quincy, Saher IV de, 1st Earl of Winchester  b. say 1150, d. 3 Nov 1219
Robert, John Fitz  b. bef. 1191, d. bef. 20 Feb 1241
Roos, Robert de  b. abt. 1172, d. bef. 23 Dec 1226
Say, Geoffrey de Sir, Knt.  b. say 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