Monstar

Not to be confused with Monster.

“Whaaat! Youuuu will regret this!”

—Monstar, Paper Mario

This is the translation of the text from right to left:"I won't let you pass by here!" "Aah!" "It's a monster!"

Monstar is a ghost-like monster from Paper Mario. This creature appears and ambushes Mario and his partners as they approach the outskirts of Starborn Valley, where it warns them to "turn away" and "go no further", lest they be "eaten". The player will then be presented with the choice to either flee the area or fight; choosing the latter option will initiate the battle.

Despite an intimidating appearance and an attack consisting of a flurry of shooting stars, Monstar is actually revealed to be an easily defeated boss, having only 20 HP and an attack power of 1. Upon its defeat, the creature is revealed to be nothing more than a handful of Star Kids trying to protect the valley, who attempt to give one last warning to flee before retreating.

It is worth noting that during battle, Monstar is immune to the powers granted by the Star Spirits as well as the Shooting Star item, no doubt because of the Star Kids acting as its sustenance.

Monstar also appears in the 27th issue of Super Mario-Kun. It terrifies and attacks Mario, Goombario, and Kooper, but when Mario defeats it, many Star Kids reveal themselves and escape, surprising Mario and his group.