Details of the characters are scarce, but Agent Miller is described as "smart" and "smooth," while Agent Einstein is described as "sharp" and "confident," reported Aceshowbiz.
They, however, will appear in only one episode.
Sharing his excitement to join the show, Amell, who has a recurring role as Firestorm on "The Flash" wrote on his Facebook page, "I guess the news is out. I'm so excited to be a part of The X-Files reboot!!"
The six-episode event series will launch with a two-night premiere on Sunday, January 24 and Monday, January 25 on FOX.