Giant rat of Argon
The giant rats of Argon were creatures which threatened the fantasy world of Ecord, being ordinary rats turned into monstrous, enlarged creatures by the Shamen of Argon. Jenny Everywhere was attacked by one almost immediately after arriving in Ecord, before meeting up with Tyse and being informed that it was only one of many. Together they rode to the Temple of Argon where they found many more kept in cages by the Shamen; the High Priest ordered his minions to release them to delay the intruders, but the two were able to fight them off with little trouble. (PROSE: Jenny Everywhere and the Eye of Argon)
Behind the scenes
In the original Eye of Argon, the protagonist faces and kills a giant rat, but it is not explicitly stated to have any relationship to the Shamen of Argon.