Fox Mulder (David Duchovny) and Dana Scully (Gillian Anderson) have come face-to-face with many monsters over the years on "The X-Files." The two haven't seen a monster since The X-Files closed in 2002, but that's going to to change when episode 3 of the miniseries, "Mulder and Scully Meet the Were-Monster," airs Monday night. 

Will the "were-monster" become one the most terrifying creatures to ever show up on "The X-Files"? Before fans get a look at an all new creature, here are eight of the scariest monsters to appear on "The X-Files" TV series.

1. Flukeman

The Flukeman is arguably the scariest monster to ever appear on the sci-fi drama. The mere sight of the creature will stick with you long after you watch episode 2 from the second season, titled "The Host." The Flukeman roams sewers in New Jersey in the episode and it's believed he is the product of the Chernobyl disaster in Russia.

2. Tooms

While not as creepy looking as the Flukeman, Eugene Tooms is a serial killer that is also an ancient evil. Tooms has the ability to contort his body so he can squeeze into any opening or crevice to get to his victims. This monster appears in two episodes in Season 1, "Squeeze" and "Tooms."

3. The Peacocks

The Peacock family are the main villains in "Home," one of the most notorious and terrifying episodes of the series to ever air. The Peacocks are a family of inbred killers, who get their kicks on murdering babies. "Home" is episode 2 of Season 4.

4. Rob Roberts

Roberts is basically a more frightening version of Jaws from the James Bond movies. He is a mutant that feeds on brains to satisfy his hunger and to survive. You can catch Roberts in Season 7, episode 3, "Hungry."

5. Mothmen

Based on the urban legend, the mothmen found in Season 5, episode 4 "Detour" can also keep you up at night. This monster has red eyes and can blend into trees, appearing to be bark.  The final moments the mothmen are shown in the episode will give you chills, as a pair of red eyes are shown under the bed in Scully's hotel room.

6. Phyllis Paddock

Phyllis Paddock was the substitute teacher from hell in Season 2, episode 14, "Die Hand Die Verletzt"...literally. Paddock had some sort of demonic background, though it was never confirmed that she was actually a demon. She terrorized a high school in New Hampshire by killing students and walking around with disturbing green eyes.

7. The Beggar Man

The Beggar man debuted in Season 8, episode 10, "Badlaa," meaning Mulder wasn't around to have to deal with him. Scully and her new partner John Doggett (Robert Patrick) face an Indian mystic, who was a murderer that went around pretending to be poor. The Beggar man used his hands to move around on a cart. After he killed someone, he would then hide in the victim's stomach to make it appear as though the person was still alive.

8. Leonard Betts

Leonard Betts was such a monster, that Season 4, episode 12 was named after him. Betts eats cancer out of victims and can grow back body parts if they are cut off. Despite being a creepy mutant, Betts made Scully aware that she had cancer after he kept trying to chase her down at the episode. Scully battling the illness would become an important storyline through Season 5 on the show.

"The X-Files" miniseries continues Monday, Feb. 1 on Fox at 8 p.m. EST.