Manu Bennett, a fan favorite from the Spartacus TV series, will portray Slade Wilson in the CW’s Arrow TV series.  As comic fans are well aware, Slade Wilson is the alter ego of Deathstroke, a major DC villain created by Marv Wolfman and George Perez in The New Teen Titans #2 in 1980.  The Deathstroke character has already made an appearance on Arrow where he was seen in costume (played by another actor) in a very brief flashback scene. 
Bennett will appear as Slade Wilson in multiple episodes of Arrow, some of which will include flashbacks to the South Pacific island of Lian Yu where Oliver Queen and Wilson were marooned together and formed an uneasy alliance. 
According Entertainment Weekly, Wilson will continue to appear as the Gaul Crixus in the final season of the Spartacus TV series, while filming multiple episodes of Arrow for this season.  No word yet on when Bennett’s Slade Wilson will shed his normal identity and get in costume as Deathstroke/Terminator.  Bennett, who is from New Zealand, will also play an Orc Chieftain in Peter Jackson’s Hobbit films.