Spore King
The Spore King is the villain of Toad Force V, a popular television program (with a Star Trek-like fanbase) mentioned in Mario Party Advance. (It is unknown if any other major villains exist in the series; if so, he is among their ranks.) Despite the fact that a surprisingly large amount of information is known about Toxic Toad Z, one of his henchmen, very little is known about this more major villain.
In all of Mario Party Advance, only one reference is made to the Spore King. This single reference is made when selecting the "Toxic Toad Z Figure." option at Junk during Lantern Ghost's Nerd Force V mission. When this option is selected, Paratroopa will proclaim the character a "hard-core fan" of Toad Force V and begin spilling out information regarding Toxic Toad Z; as he does this, he mentions the Spore King (who happens to own the robotic Toxic Toad Z) a few times. In these mentions, Paratroopa describes how the Spore King, perhaps the main antagonist of Toad Force V, "outguns Toad Force V" (meaning that he overwhelms the group of protagonists with an amount of weapons surpassing theirs) and how he ruthlessly plagiarized Toxic Toad Z's design from plans stolen from a Toad laboratory.
These few mentions leave much to be learned about the Spore King. While his name suggests royalty, it is unknown if he actually governs anything. The "Spore" part of his name is also taken from the word "spore", which is used to describe a seed-like reproductive vessel used by fungi. This fungus-inspired name suggests that he, like Jack, is a Toad.