Before "Arrow" Season 5 thunders to its conclusion, Deathstroke will return to the series. On Twitter, star Stephen Amell confirmed that Manu Bennett will reprise his role as Slade Wilson.
— Stephen Amell (@StephenAmell) April 10, 2017
While Deathstroke's return is certainly a surprise, it syncs up with a comment that executive producer Wendy Mericle gave last last week. “The alliances are going to be very surprising,” she told Entertainment Weekly. “You’re not going to believe who Oliver is working with to defeat Prometheus. It’s going to be really emotional. It’s going to be all about Oliver’s family, but not the family we’re thinking of right now. It’s going to end in a giant explosion, but not where we think it’s going to end, and the emotional punch is going to be bigger than the actual physical part of the bombs going off.”
Seeing as the image of Deathstroke's helmet came paired with the comment "Desperate times call for desperate measures," it seems very likely that Oliver will call on Slade to help him take down Prometheus. Amell tagged Bennett specifically, which is important to note, seeing as Deathstroke appeared in the show's 100th episode was not played by Bennett himself.
Bennett last played Deathstroke in the Season 3 episode "The Return," which found Oliver and Thea on Lian Yu. On the island, they encountered Slade, who had been imprisoned there by A.R.G.U.S. Oliver and Thea came to blows with Slade, only for them to lock him up once again. This was the last time Deathstroke appeared on the series, with the exception of his voiceless appearance in the 100th episode.
Slade played a critical role over Season 1 and Season 2 of "Arrow." In Season 1, Slade became a friend of Oliver's as they both suffered through life on the island. By the time of Season 2, he returned to civilization with one goal: to make Oliver's life hell. Slade fully became Deathstroke in this season, even donning the character's signature orange-and-black costume. Team Arrow eventually overcame Deathstroke and his army of mirakuru-powered soldiers, which landed Deathstroke in A.R.G.U.S. custody.
Starring Stephen Amell as the Emerald Archer, “Arrow” airs Wednesdays at 8 pm ET/PT on The CW. The series also stars Emily Bett Rickards, David Ramsey, John Barrowman, Willa Holland and more.