Kerborg, or Kerbog, is Lord Darkar's personal pet. He is a batlike shadow monster distinguishable from the others.
In Party Monster, Darkar transformed Kerborg into a monster, Liodragarus, to attack Red Fountain as a distraction while the Trix attempted to steal the codex. With help from Helia, Sky, Brandon, Riven, and Timmy stabbed him in the throat, destroying his monster form, but Kerborg survived in his original form and returned to Darkar.
When Bloom was turned into Dark Bloom, she took Alfea's codex and gave it to Kerborg, who delivered it to Darkar.
When the Winx and specialists entered Shadowhaunt, Darkar transformed Kerborg into a knightlike monster and set him to guard his base. The Winx fought against him before Faragonda, Griffin, and Codatorta appeared. Kerborg was immune to magic in this form, but Faragonda and Griffin cast a spell to power up Codatorta, who broke Kerborg's back, destroying his monster form again. In his original form, Kerborg tried to fly away, but Faragonda and Griffin destroyed him with an energy ball.