Enter Mallus. In a new photo, Fringe alum John Noble appears on the set of DC's Legends of Tomorrow wearing a long gray wig and a fabulously furred robe with wide sleeves, in what's likely a reference to his Lord of the Rings character Denethor.

Since "Return of the Mack," Noble has lent his voice to the demon Mallus for four Season 3 episodes. Now, in an episode appropriately titled "Guest Starring John Noble," the actor will show up in the flesh. In the photo, Noble exits a trailer to meet Brandon Routh's Ray "The Atom" Palmer. The two appear to be comparing notes.

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According to the episode description,

SEEING DOUBLE -- With the timeline barely stable, the Legends must tackle two anachronisms at the same time to try and keep Mallus at bay. Sara (Caity Lotz) and Rip (guest star Arthur Darvill) team up to stop Grodd (guest star David Sobolov) from going after a particular target leaving Nate (Nick Zano) and Wally (Keiynan Lonsdale) to stop Amaya (Maisie Richardson-Sellers) from changing her future. Meanwhile, the Legends think they have found a way to destroy Mallus, but they will have to create an uneasy alliance with one of their enemies. Brandon Routh, Dominic Purcell and Tala Ashe also star. Ralph Hemecker directed the episode written by Keto Shimizu & James Eagan (#317). Original airdate 4/2/2018.

Airing Mondays at 8 p.m. ET/PT on The CW, DC’s Legends of Tomorrow stars Arthur Darvill as Rip Hunter, Dominic Purcell as Mick Rory/Heat Wave, Caity Lotz as Sara Lance/White Canary, Brandon Routh as Ray Palmer/Atom, Maisie Richardson-Sellers as Amaya Jiwe/Vixen, Nick Zano as Nate Heywood/Steel and Keiynan Lonsdale as Wally West/Kid Flash.

John Noble appears on the set of DC's Legends of Tomorrow in a new photo.