The Shipbreaker is an unique fog crawler who has haunted Mount Desert Island for decades. The time spent in the Fog has apparently mutated her, so that she gives off an unique radio signature that interferes with regular radio equipment. Old Longfellow has spent a lifetime tracking the beast and would like to take his revenge on her - for all the deaths she has caused and friends she took from him. Unlike other fog crawlers, the Shipbreaker is also unusually vicious and destructive, killing for sport, rather than out of necessity. Taking her out is as much personal as it is a public service to the people of Far Harbor.
The name was bestowed on her by Old Longfellow, who started the hunt for the Shipbreaker a few years back, when wrecked boats and dead people started washing up on the shores. The reports eventually gave him a clear picture and he dedicated himself to the hunt ever since.