Princess Shroob

"YOU INTERLOPERS WILL BE CONSUMED!"

- Princess Shroob

Princess Shroob is the main antagonist of the game Mario & Luigi: Partners in Time. She is second in command of the alien race known as the Shroobs, although initially it appears that she is their leader. She set off a full invasion of the Mushroom Kingdom to make it their own. She and her vast army of Shroobs attacked the Mushroom Kingdom of the past. Princess Peach arrives at that point in time in Professor E. Gadd's Time Machine and is immediately attacked by her twin sister. Princess Peach managed to seal her soul inside the Cobalt Star, which she shattered it into six pieces. The younger Princess Shroob, out of anger, attacked Princess Peach and sealed her inside her own castle of the past, which had been transformed into Shroob Castle. Possibly because Peach held the sixth Cobalt Star Shard, the Shroobs kept Peach unharmed and in perfect condition, aside from attempting to feed her to Petey Piranha. It is unknown if they actually did feed her to Petey Piranha, as the Princess Peach they rescued later in the game was revealed to be a fake. Her appearance vaguely resembles Princess Peach.

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 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.

The four Mario Bros. eventually make their way through a 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 appears to have gone mad, declaring Peach useless, the kingdom was already hers, and that she will destroy them all, shouting "Destroy!" several times. She then goes into battle with the bros. on her battle throne which can shoot lasers and change into a giant walker robot, it also protected by a forcefield that the bros. need to shut down. When outside her forcefield, she can teleport and attack the brothers with disk-shaped lasers from her hands, as well as summon a laser star that will keep heading toward the Mario Bros until it hits or is stomped on.

After beating the princess, she lies on the floor, near-death. When Baby Bowser puts together the Cobalt Star, she crawls to where the Mario Brothers are, and shouts that it is her sister's turn now to fight them. She then dies and, like previous bosses, brilliantly explodes.

The Cobalt Star shards are located in many places that Princess Shroob should have been aware of, such as the Vim Factory. It is unknown why she did not attempt to have the Cobalt Star restored and bring her sister back to power.

In Mario & Luigi RPG 3, Princess Shroob can be seen frozen in the background of a battle of Mario and Luigi against three Shroobs in Bowser's castle.