Final answer:
The hero of one of the first Spanish epics from around 1140 is El Cid, described in 'The Poem of the Cid' or 'El Cantar de Mio Cid'.
Step-by-step explanation:
The Spanish hero who is the subject of one of the first epics in Spanish literature from around 1140 is El Cid. The epic poem is titled “The Poem of the Cid” or “El Cantar de Mio Cid” in Spanish. This poem narrates the adventures of the Castilian nobleman Rodrigo Diaz de Vivar, known as El Cid Campeador. It is a valuable historical document that also gives insights into Spanish medieval society.