Grendel's Mother

From being described a witch to a demonic figure, She wanted to avenge her son's death by killing his killer, which in this case is Beowulf. She baits Beowulf by killing off some of his men and taking the arm to restore her son's body.

She even ambushed Beowulf in her cave in an underground cavern beneath the moors. She breaks Hrunting that Unferth gave to Beowulf, only to be killed by the ancient sword of Schyld.

Versions
From an Ogress to a Siren. She in the 2007 version had no maternal instincts and lets her "sons" do her dirty work, hides behind a facade of a beautiful woman like a coward and makes a deal with her son's killer.

The version is based on Angelina Jolie's performance instead of being true to the story, it was made out of greed and pleasure, which Grendel's mother was seen as an embodiment of.