Spider Demons are a type of Demon.
At the market, the Spider Queen convinces Pigsy and Tang to going inside her store after Pigsy fell in love with her. However, when she did, she sent Pigsy and Tang down a hole to the Silken Web Cave.
At the Silken Web Cave, Tang blames Pigsy for their capture until the Spider Queen arrives, who explains her plans to take back her empire while planning to eat Pigsy and Tang. When Tang mentions that MK will come for them, the Spider Queen decided to wait for MK's arrival.
Once MK, Mei, Sandy, and Mo ventured across the Silken Web Cave, the Spider Queen captures them and goes after MK. Once the Spider Queen confronted MK, she takes a piece of his hair and says that she'll take his powers so it can be hers. However, MK's Team returned and attempt to rescue MK, but only for the Spider Queen to attack MK again until she unintentionally caused a giant hole in the ground, causing MK's Team and the Spider Queen to fall down.
Although, the Spider Queen was able to save herself and says it wouldn't be the last MK and his team seen of her after she got what she wanted.