Sun (Paper Mario)
From the Super Mario Wiki
The Sun, a.k.a. The Blessed Sun, is a celestial entity that lives in the Sun Tower at Flower Fields. Like the Star species, the Sun is not the gigantic star that Mushroom World orbits. In fact, this Sun is only slightly bigger than Mario. The Sun is, in actuality, a local sun that can provide extra amounts of sunlight to small regions (not entire planets). As such, this Sun provides the necessary amount of light needed to sustain the abundance of plant life in Flower Fields.
During the events of Paper Mario, Bowser's minion Huff N. Puff covered Flower Fields with a continuous stream of clouds from his Puff-Puff Machine. Of course, a little cloud cover now and then is normal. However, continuous cloud cover prevented the Sun's rays from reaching the floral residents of Flower Fields. Unfortunately, if this continued for too long, all the plant-life of Flower Fields would wither away and die from lack of sunlight, allowing Huff N. Puff and his forces to rule the region unopposed.
Fortunately, Mario and his allies, with the help from their new comrade Lakilester, destroyed the Puff-Puff Machine before any deaths occurred. With the clouds gone, the Sun could return to the sky and send its energy to the plants of Flower Fields. Additionally, with sunlight returned to the area, Mario could grow a magic beanstalk to take him to Cloudy Climb, the site of the evil Huff N. Puff and the imprisoned Star Spirit Klevar.