The hottest stars are the blue hypergiants, the hottest and most massive star found to date is called R136a1. It is thought to be around 40,000 to 50,000 Kelvin at the surface, while the core maybe several billion degrees.
All stars have different temperatures, depending on their mass and period in their life cycle. The hotter a star is, the brighter it will appear.
The stellar classification [See link] in order of...
well, stars are balls of gas (hydrogen) which fuses into helium. is also how how the sun produces energy but stars can reach a temp. of 20,000 if purple if it is blue probley 10,000
A red star can be 2,600-3,850 degrees C.
A red-orange star can be 4,000-5,250 degrees C.
A yellow star can be 5,500-6,000 K degrees C.
A white-yellow star can be 6,000-7,200 degrees C.