1. India: Tamil is one of the 22 scheduled languages of India, and it is the official language of the state of Tamil Nadu. It is also spoken in parts of Kerala, Karnataka, Andhra Pradesh, and Puducherry.
2. Sri Lanka: Tamil is one of the two official languages of Sri Lanka, along with Sinhala.
3. Singapore: Tamil is one of the four official languages of Singapore, along with English, Malay, and Mandarin Chinese.
4. Malaysia: Tamil is one of the official languages of the state of Penang in Malaysia.
It is important to note that while Tamil is an official language in these countries, it is not necessarily the most widely spoken language in all of them. For example, Sinhala is spoken by a larger percentage of the population in Sri Lanka than Tamil.