1. Red: Red dragons are the most powerful and sought-after dragons in the Avatar world. They are known for their immense strength, destructive power, and fiery breath. Sozin's Comet is a red comet that greatly amplifies the power of firebenders and dragons.
2. Green: Green dragons are considered wise, ancient, and guardians of knowledge. They are often depicted as mentors or guides for humans.
3. Blue: Blue dragons are associated with water and are depicted as protectors of the oceans. They are skilled in waterbending techniques.
4. Yellow: Yellow dragons, also known as "Sun Dragons," are rare and powerful. They possess the ability to breathe sun-fire and are closely tied to the spirit world.
5. Purple: Purple dragons are associated with royalty and prestige. They are considered rare and highly venerated in certain cultures.
While these are some commonly known dragon colors in Avatar: The Last Airbender, it's worth noting that there can be variations and other unique colors mentioned or depicted throughout the series.