'Deathstroke', debuting in DC's "The New Teen Titans" #2 is a mercenary, genetically augmented by the government to be the perfect soldier.
According to executive producers Greg Berlanti and Marc Guggenheim, there will be numerous 10 DC Comics characters that will appear on "Arrow" includng :
'Felicity Smoak-Raymond' debuting in DC's "The Fury of Firestorm #23 , appears in the series as the manager of a computer software company who takes up the fight to keep 'Starling City' clean.
'Walter Steele', debuting in DC's "Green Arrow' Vol 4 #1, is the new CEO of 'Queen Industries'.
'Merlyn', debuting in DC's "Justice League of America" #94 appears as a villainous archer and member of the deadly 'League of Assassins'.