The new official term for a Massachusetts native is Massachusett. This pays homage to the indigenous people of the land who called themselves the Massachusetts (singular: Massachusett)
"Well, here are all the options I've found. Massachusian with 70 hits in Google seems to be the most frequently used of the morphs of the state name....but among these, Bay Stater is the expression more frequently used. I think "resident of Massachusetts" beats them all for frequency of use. ;o))
Bay Stater, Massachusite, Massachusian, Massachusettser, Massachusetter, MassachusetteanLocal perspective: The answer depends on your geographical and psycological point of view. Outside of MA, we are frequenly called Massholes, particularly by the gracious folk of New Hampster. The term Bay Stater is favored by our happier residents, and in particular our media mavens, because it is so much easier to prounounce than Massachusettser, etc. Malcontent residents might be more inclined to refer to us as Taxachusettsers.