“More, Rowle, or shall we end it and feed you to Nagini? Lord Voldemort is not sure that he will forgive this time. . . . You called me back for this, to tell me that Harry Potter has escaped again? Draco, give Rowle another taste of our displeasure. . . . Do it, or feel my wrath yourself!”
-- Voldemort (DH9)
Thorfinn Rowle was a Death Eater during the second war with Voldemort.
He is described as being a large blond man. During the Battle of the Astronomy Tower, Rowle threw multiple curses at Hagrid then set his hut on fire with Fang the dog inside before running away with Snape, Draco and the Carrow twins (HBP28).
Rowle along with Death Eater Antonin Dolohov attacked Harry, Hermione and Ron in the Muggle cafe in London when the Ministry fell to Voldemort. Harry recognized him from the night Dumbledore died, while Ron knew his name from a wanted poster (DH9). Hermione Obliviated the memories of Rowle and Dolohov so they would forget about fight.
Later that night, Harry had a vision through his scar of Voldemort forcing Draco to perform the Cruciatus Curse on Thorfinn for letting Harry escape. This punishment was remembered by Draco’s mother Narcissa when the Snatchers had captured a disguised Harry and the Death Eaters were debating whether to call Voldemort to Malfoy Manor: “If we are mistaken, if we call the Dark Lord here for nothing . . . Remember what he did to Rowle and Dolohov?”
Harry saw Rowle in the Forbidden Forest with an injury to his lip from fighting in the Battle of Hogwarts (DH34). As Harry surrendered there to Voldemort and prepared to die, Hagrid shouted “No!” and Thorfinn silenced him.
One possible ancestor of Thorfinn, Damocles Rowle, was Minister for Magic from 1718-1726 (Pm).
Possibly a reference to the 10th-century Viking Earl of Orkney Thorfinn Torf-Einarsson known as "Thorfinn Skull-Splitter"
From the Web
"Thorfinn Rowle" from Harry Potter Wiki