Other than a mild hullicination of him after an explosion, Jax is never visited by his father’s ghost…not in the same sense Hamlet was. He is, however, haunted by him through his writings.
John Teller, Jax discovers, was a man of great moral responsibility. He wanted a better life for his children and his club. He wanted that subversive comfort that comes from non-conformity and he wanted his son to have the same peace he sought.
The King of Denmark, whether he was actually a ghost or a figment of Hamlet’s grief, sought revenge. While John doesn’t ask Jax to avenge his death, (which later seasons claim Clay and Gemma were responsible for), the secrets Jax uncovers, initiates revenge, retaliation and the need for alliances that will see his father’s murderer brought to justice.