Final answer:
Osiris became the lord of the underworld after his resurrection, transitioning from the earthly ruler to the divine judge and king of the dead.
Step-by-step explanation:
After the resurrection of Osiris, he did not return to his role as the king of Egypt; instead, he became the lord of the underworld. In this capacity, he presided over the realm of the deceased, a critical element of the Egyptian concept of the afterlife. As the king of the dead, Osiris was responsible for the judgment of souls and represented the eternal cycle of death and regeneration. Meanwhile, his son Horus contended with Seth and, after being declared the victor by the earth god Geb, became the new King of Egypt.