Arachnians

First encountered in the lair of Aram-Dol in Ultima VII Part Two: Serpent Isle, Arachnians are among the many deadly guardians of Serpent's Fang.

In years past, by means of the blackest sorcery, the arch-liche took many of his human prisoners and fused their torsos with the bodies of giant spiders. Cunning and fearsome fighters, these grotesque half-breeds are known to eat their prey alive. They are also fond of shooting their foes at range with magic arrows. Thankfully, they possess a natural vulnerability to fire.

Luckily, Arachnians are rarely encountered off the Serpent Isle.

In Ultima Online
In Ultima Online, a species of spider-human hybrids called Terathans appear. They are very similar to Arachnians and they may in fact be the same creatures. The Terathans seem to have a caste social structure with matriarchs, warriors and drones. 

Trivia

 * It appears as though Arachnians were to be included in the cancelled Ultima X, although the shown picture is not specifically described as such. Link: Ultima X Arachnian?.