Dee Bradley Baker, Ben Diskin, Tom Kenny, Cree Summer, Lauren Tom, and others (Nerd Zombies), Tom Kenny (Giant Nerd Zombie, Operation: U.N.C.O.O.L.), Dee Bradley Baker (Giant Nerd Zombie, Operation: I.N.T.E.R.V.I.E.W.S.)
Nerd Zombies are, as their name implies, undead forms of nerds that are activated if something of value (usually petty collectibles such as trading cards, which nerds are obsessed with) is stolen from a nerd. They then relentlessly search for the thief and will only stop when the item is retrieved. Nerd Zombies are featured in Operation: U.N.C.O.O.L., where they attack the Sector X Treehouse after Yipper card #78 is stolen from them by Numbuh 42. After the card is finally given back and the nerds revert to their normal selves, the nerds tie up the KND and force them to watch reruns of "Doctor time space and the continuum". The leader of the Nerd Zombies, who is noticeably larger than the rest, is voiced by Tom Kenny. The zombies later appeared in Operation: I.N.T.E.R.V.I.E.W.S. in which Stickybeard and his pirates steal the the same card from them during the scavenger hunt and invoke the wrath of their zombie forms.