All fallacies are non-sequiturs.
From Wikipedia
An ad hominem (Latin: "to the man"), short for argumentum ad hominem, is an attempt to link the validity of a premise to a characteristic or belief of the person advocating the premise.
Ad Hominem is not always a fallacy. For instance, it would not be possible to assess a person for a position without considering that person's characterstics. Sometimes we neither have the resources to assess a claim based on anything other than the characteristics of the one who made it.