* Harvey is an invisible rabbit. No one physically sees Harvey, only Elwood P. Dowd does.
* The play focuses on the perception of Harvey. The characters who believe Elwood is crazy see Harvey as a symptom of his delusion. Those who believe Elwood (like his niece, Veta) come to accept Harvey's presence, even if they can't see him.
So, to answer your question directly:
* No one literally sees Harvey, except Elwood.
* However, the play's ending suggests a change in perspective. The characters who were initially skeptical of Harvey's existence begin to accept the idea that he might be real, even if they can't see him.
Let me know if you'd like to discuss more about the themes of perception, reality, and belief in the play!