Highlander alum Adrian Paul made a surprise debut on Monday's Arrow episode as the shadowy villain Dante. Diggle (played by David Ramsey) and Lyla (Audrey Marie Anderson) have been investigating the identity of the Dante character for several episodes now, as it had been realized he had been funding dozens of terrorists attacks and sent in the Longbow Hunters.
In comic books, Dante is the leader of group of villainous bankers known as the Ninth Circle. The group debuted in 2016's Green Arrow: Rebirth #1.
Paul is best known for playing Duncan MacLeod in the 1990s syndicated TV show Highlander: the Series.
Arrow continues next Monday with the "Training Day" episode.