Sun

The Sun is a mass of incandescent gas, a gigantic nuclear furnace where hydrogen is built into helium at a temperature of millions of degrees. Humans like to call their star "the Sun," but the word "sun" can also apply to any star with a planetary system. Such systems are typically composed of planets, asteroids, and giant eggs that look like asteroids.

Since Transformers typically spend their time on planets, suns are much more common in their adventures than bare stars.

Earth's Sun
Properly called "Sol," this sun is a frequent target of the Decepticons, who seek to utilize it in various ways, such as tapping into its power, hurling things such as Autobots or the planet Earth into it, or just plain blowing it to smithereens. The Autobots usually stop them in time, but it's almost always a close call.