Yes, Achilles is in
The Odyssey, but as he died before the events of the epic, Odysseus encounters his ghost (or "shade") when he travels to the Underworld.

SparkNotes
Their interaction is one of the most famous and emotional scenes in Homer's poem:
- The Meeting: Odysseus praises Achilles for his legendary heroism and glory, and assumes he must still be a mighty king among the dead.
- The Regret: Achilles replies with profound sorrow, famously telling Odysseus that he would rather be a poor, living serf on earth than to rule over all the dead in the Underworld.