X-Yux

X-Yux appeared in 2004 video game called Paper Mario: The Thousand-Year Door. X-Yux is an upgrade of the original Yux found in Paper Mario: The Thousand-Year Door. According to Goombella, its name is pronounced "Cross-Yux" instead of "Ex-Yux", although she opens her tattle with "That's an X-Yux", suggesting that she used the incorrect pronunciation before reading the correction.

A solitary X-Yux is used as the guard of Grodus' room in the X-Naut Fortress. Additionally, if three questions of the 66th Annual Quirk Quiz are answered incorrectly, the player will have to face two X-Yux. In battle, a X-Yux spawns two Mini-X-Yux each round, up to a maximum of four per X-Yux. As such, it is invincible while Mini-X-Yux are surrounding it. When a X-Yux is surrounded by four Mini-X-Yux, it shoots five beams at Mario and his partner. They will likely be immobilized, being set up for an endless combo, and thus preventing retaliation.

The X-Yuxes, as with the rest of the Yux family, are notable in that their beam attacks pierce all Defend Plus and Damage Dodge badges that Mario and his partner have equipped. This means that their attacks and immobilization can only be defended against with the use of Guards and Super guards.