With The Flash set to return later this month from its holiday hiatus, The CW series has added yet another new guest star, with Liam McIntyre (Spartacus) signing on to play Mark Mardon, a.k.a. The Weather Wizard. Fans may recall that, in the Pilot episode, Mark's brother Clyde Mardon (Chad Rook) appeared as The Weather Wizard. Mark Mardon will appear in the 15th episode and 16th episode of the season, using the same sort of weather-controlling abilities as Clyde, to find the man who killed his brother, Detective Joe West (Jesse L. Martin).

The 16th episode, entitled Rogue Time, will also feature two more sibling guest appearances. We reported in December that both Lisa Snart (Peyton List), the sister of Captain Cold/Leonard Snart (Wentworth Miller) and Dante Ramon (Nicholas Gonzalez), older brother of Cisco Ramon (Carlos Valdes), will be appearing in Rogue Time, although it still isn't clear when this episode may air. It remains to be seen if all three of these siblings will cross paths in Rogue Time.

The Flash will return with its midseason premiere Revenge of the Rogues on Tuesday, January 20 at 8 PM ET on The CW. Liam McIntyre is best known for playing the title character on Starz's Spartacus, a show that CW's Arrow has drawn from several times in the past. Manu Bennett (Deathstroke), Cynthia Addai-Robinson (Amanda Waller), Katrina Law (Nyssa al Ghul) and Nick Tarabay all previously starred in Spartacus before being cast in Arrow.