Commonly used:
1. सूर्य (Soorya): This is the Sanskrit word for Sun, commonly used in Tamil as well.
2. இரவி (Iravi): This word is specifically associated with the Sun's role in the day (ravi meaning day).
3. ஞாயிறு (Nyaayiru): This word refers to the Sun as the source of the day of the week (Nyaayiru is Sunday).
4. தெய்வநாயகன் (Theivanaayagan): This literally means "Lord of Gods" and is used to refer to the Sun as a deity.
Less common, but still found:
5. கதிரவன் (Kadiravan): This word emphasizes the Sun's rays.
6. சூரியன் (Sooriyan): Another commonly used Sanskrit derived name.
7. பகலவன் (Pagalavan): This word highlights the Sun as the source of day time.
8. நிலா (Nila): This word actually refers to the Moon, but it's used as a metaphorical name for the Sun in some poetic contexts.
There are many more obscure or regional names for the Sun in Tamil, depending on the context and region. These are just some of the most commonly used ones.