Who is the Trojan hero killed by Achilles and dragged around the town's walls?

The hero you are referring to was Hector, a Trojan prince, first-born son of King Priam and Queen Hecuba and the greatest fighter for Troy in the Trojan War.

When they battled face-to-face, Achilles stabbed Hector through the chest and despite Hector's pleas for an honorable burial, he slit Hectors heels, threaded the girdle that Ajax had given Hector through the slits, then fastened the girdle to his chariot and drove it around Troy's walls.