Final answer:
The Titan who stole fire from the gods and gave it to mankind, and as punishment was chained to a rock and had his liver eaten by an eagle, is Prometheus.
Step-by-step explanation:
The Titan in question, known for his trickster nature and for stealing fire from Zeus and the gods and giving it to mankind, is Prometheus. He was indeed a champion of humanity and was punished harshly for his benevolence towards humans. For his transgression, Prometheus was chained to a rock, and an eagle was sent by Zeus to eat his liver, which would regenerate every day as part of his eternal punishment.