Princess Shroob

Princess Shroob is the primary antagonist for the majority of Mario and Luigi: Partners in Time. She is the second-in-command of an alien race, the Shroobs. Although initially it appears that she is their leader. She resembles the rest of her race in color, but is taller with a proportionally smaller head, and wears a dress, similar to Peach's dress. She is the 1st of the three final bosses of the game.

Biography
The Shroobs are got tired of living in their planet and wanted a new home so Princess Shroob set off a full invasion of the Mushroom Kingdom to make it her own. She takes over Peach's Castle, turning it into the Shroob Castle. The castle towers were changed into tall purple mushrooms, along with all the pillars and bushes, and even a statue of herself got built.

In the present, the Professor E. Gadd made a time machine. The machine was first used by Princess Peach who goes to visit the Mushroom Kingdom's distant past. She unfortunately came into the time in which the kingdom was invaded by the Shroobs, so she got captured and imprisoned by Princess Shroob. A green shroob then comes back to the present with the time machine, and was then unusable since the Cobalt Star has been shattered into 6 pieces. A while later, a tear in the space-time continuum, known as a time hole, opens, leaving a passageway into the past. While searching for Peach, Mario and Luigi locate their younger selves, and agree to locate the crystal shards, which are remnants of the Cobalt Star which had been shattered, since they where told that they needed five Cobalt Star shards to gain access to the Shroob Castle.

When Baby Mario, Baby Luigi, Mario, and Luigi rescue Peach in Gritzy Caves, she had a purple mushroom attached to her face. She is later revealed to be Princess Shroob in disguise who had the intention of taking over the present Mushroom Kingdom as well as the Mushroom Kingdom of the past. It seemed Baby Peach was the only one knowing as she cried at her.

After acquiring five shards, the four Mario Bros. eventually make their way through the shroobified Peach's Castle and hijack a Shroob Battleship and engage the Shroob Princess in a dogfight. After blasting the Shroob Mothership out of the sky the Princess emerges out of it. She then enters battle with them.

After she is defeated, Mario, Luigi, and their baby selves free Princess Peach. Mario and Luigi explained her that they were searching for Cobalt Star shards, after which Peach shows the last shard and tells them that she cannot allow them to reassemble the Cobalt star. Before she can explain, Baby Bowser, who was hiding in the Mothership, drops in, putting the last Cobalt Star Shard in the Cobalt Star. Peach then explains that Princess Shroob had a twin sister (who actually looks nothing like her), and that Peach sealed Elder Princes Shroob in the cobalt Star, thereafter shattering it into pieces. Reassembling the cobalt star liberated Elder Princess Shroob from the cobalt star, destroying the cobalt star in the impact. Princess Shroob was thought to be the main villain for quite some time.