Pap Finn is Huckleberry Finn's biological father. He is an abusive, illiterate alcoholic with a perpetually disheveled and unkempt appearance, noted for his ghostly white skin, tattered clothing, and slovenly demeanor. He possesses no redeeming qualities.

Pap Finn neglects Huck for long stretches, returning only to demand money or exert control. He subjects Huck to constant physical abuse, verbal harassment, and psychological torment, sober or drunk. He relentlessly targets Huck's acquired wealth to fund his alcoholism. Pap vehemently opposes Huck's education and societal integration fostered by the Widow Douglas, seeing them as threats to his authority and signs of Huck's undeserved elevation. This opposition leads Pap to forcibly remove Huck from the Widow's care and imprison him in a remote cabin, intensifying the abuse.

Pap Finn's actions are driven by bitter jealousy of Huck's circumstances, greed for Huck's money, and deep-seated racism. He expresses virulent prejudice, criticizing the legal rights of African Americans and expressing outrage at a Black person voting. His behavior is consistently self-destructive and antisocial.

His abusive actions directly cause Huck to fake his death and escape, initiating the main adventure. Pap Finn dies during Huck's absence, shot while attempting to rob an abandoned structure with accomplices. He is later identified as the dead man found by Huck and Jim in the floating house. Pap reacts negatively to any mention of Huck's mother, suggesting he may have murdered her.

Pap Finn undergoes no character development or redemption, remaining a static embodiment of cruelty, addiction, and societal failure until his death.