Final answer:
Apollo was condemned to serve King Admetus of Thessaly as punishment for killing the Cyclopes, according to Greek mythology.
Step-by-step explanation:
The king whom Apollo was condemned to serve as punishment for killing the Cyclopes was King Admetus of Thessaly.
According to Greek mythology, Apollo was banished from Olympus as a consequence of his actions and was required to serve a mortal
He was placed in service to King Admetus, where he worked as a herdsman for several years. Apollo, being a god, helped Admetus perform incredible feats, such as yoking a lion and a boar to a chariot.
Apollo's time as a servant to a mortal king was one among the many fascinating tales in Greek mythology, also encompassing figures like Hercules and his Twelve Labors, referenced in artworks such as the Farnese Hercules.