'The Flash' and 'Six Feet Under' vets, respectively, join the Fox event series as new agents.

The X-Files has added Robbie Amell and Lauren Ambrose to its upcoming event series, The Hollywood Reporter has learned.

Amell will play Agent Miller, who is described as "smart" and "smooth." Ambrose will appear as Agent Einstein, who is described as "sharp" and "confident." They'll appear in the fourth episode of the six-episode revival.

The duo's addition comes at a busy time for the event series: In addition to returning stars David Duchovny, Gillian Anderson, Mitch Pileggi and William B. Davis, guest-stars on tap include Joel McHale, The Americans' Annet Mahendru, Flight of the Conchords' Rhys Darby and Silicon Valley's Kumail Nanjiani.

Amell (The DUFF, The Tomorrow People, The Flash) is repped by WME, Protege Entertainment, Coast to Coast and Felker Toczek. Ambrose (Six Feet Under, Dig, ABC's busted pilot Broad Squad) is with UTA, Perri Kipperman and Sloane Offer.

The X-Files returns Jan. 24, 2016, on Fox.