Much to Cisco's dismay, the undead are invading "The Flash." In a new clip from "The Runaway Dinosaur," Barry's high school bully Tony, aka Girder, is back -- from the dead.

The clip -- which can be viewed in its entirety on TVLine -- finds Cisco and Iris exploring the Reverse-Flash's lab for a part. There, Cisco recounts to Iris how Reverse-Flash used to experiment on the dead metahumans, which Iris finds creepy (and rightfully so!). As they shuffle around the lab, they hear a clanging sound from another room, just before Girder demolishes the door to the freezer where his body was being kept.

"A zombie?! For real?" Cisco exclaims, as Girder breathes heavily and casts an undead eye in their direction.

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According to the official episode description,

THE FLASH -- "The Runaway Dinosaur" -- (8:00-9:00 p.m. ET) (TV-PG, LV) (HDTV) KEVIN SMITH DIRECTS -- With Barry (Grant Gustin) gone, the team must figure out a way to handle the return of an old enemy -- Girder (guest star Greg Finley). Realizing Girder is retracing his steps from his last attack, Iris (Candice Patton) volunteers to act as bait to trap him in S.T.A.R. Labs. Meanwhile, Barry fights to return to his old life. Kevin Smith directed the episode written by Zack Stentz (#221). Original airdate 5/10/2016.

Starring Grant Gustin, Carlos Valdes and Jesse L. Martin, "The Flash" airs Tuesdays at 8 pm EST on The CW.