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 b. s 1186, d. Feb 1224/25
Bigod, Roger le b. b 1140, d. b 2 Aug 1221
Bohun, Henry de b. 1176, d. 1 Jun 1220
Clare, Gilbert de Sir b. c 1180, d. 25 Oct 1230
Clare, Richard de Sir d. 28 Nov 1217
d'Aubeney, William b. bt 1148 - 1168, d. 7 May 1236
Huntingfield, William de Sir b. c 1160, d. b 25 Jan 1220/21
Lacy, John de b. c 1180, d. 22 Jul 1240
Lanvalay, William de b. s 1190, d. b 19 Oct 1217
Malet, William b. c 1175, d. b 1219
Mowbray, William de d. b 25 Mar 1224
Quincy, Saher de b. s 1150, d. 3 Nov 1219
Robert, John Fitz b. b 1191, d. b 20 Feb 1241
Roos, Robert (Sir) b. c 1172, d. b 23 Dec 1226
Say, Geoffrey de b. s 1180, d. 19 Aug 1230
Vere, Robert de b. a 1164, d. b 25 Oct 1221
Walter, Robert Fitz Sir d. 9 Dec 1235