Ilmus Pentaphraxis was a slaver in Quintinius' time in The Edge Chronicles. He was a distant ancestor of Cowlquape Pentaphraxis, who was noble and nothing like him. Ilmus was an evil, mad tradesman and slaver, who hankered after money.
Ilmus Pentaphraxis stole Maugin, a pre-termagant trog, from her colony when she was out walking her pet. He had her pet killed and took her to slavery. He wanted to unlock the secrets of her transformation by cruelly experimenting on her, but Quintinius and his father Wind Jackal found him and Maugin, and Quintinius freed Maugin.
Ilmus was not giving up, he pursued them both in his sky ship, but was shot down after a battle over the Deepwoods, and he was killed.