Guy I may refer to:
Guy I of Albon (c. 1000–1070) Guy I of Clermont (c. 1255 – 1302), Marshal of France, Seigneur (Lord) of Offemont Guy I, Count of Blois (died 1342) Guy I of Gibelet, of the Embriaco family Guy I of Luxembourg, Count of Ligny (1340–1371) Guy I of Montlhéry (died 1095) Guy I of Ponthieu (died 1100) Guy I de la Roche (1205–1263), Duke of Athens Guy I of Spoleto (died 860)
Other Guy #1, a character in We Like Sportz by The Lonely Island