Negative Numbuh 3 is the evil twin of Numbuh 3 in the Negative Universe and appears in the episode Operation: P.O.O.L.. She is the un-emotional and theoretical opposite of Numbuh 3. Unlike Positive Numbuh 3, Negative Numbuh 3 has no obvious feelings for Negative Numbuh 4 or Positive Numbuh 4, saying almost immediately upon meeting Numbuh 4, "I don't like you."