1. Turkey: With a Kurdish population estimated to be around 15-20 million, Turkey has the largest Kurdish population.
2. Iran: The Kurdish population in Iran is estimated to be around 8-10 million.
3. Iraq: The Kurdish population in Iraq is estimated to be around 5-7 million, with a large degree of autonomy in the Kurdistan Region of Iraq.
It's important to note that there are also significant Kurdish communities in Syria and other countries, but the three listed above are considered the main ones due to the size of their Kurdish populations.