| Chak Chak | |
| Native Name Lang: | fa |
| Other Name: | Chāhak-e Ardakān, Pīr-e Sabz |
| Settlement Type: | Village |
| Pushpin Map: | Iran |
| Pushpin Map Caption: | Location within Iran |
| Pushpin Relief: | y |
| Mapsize: | 150px |
| Subdivision Type: | Country |
| Subdivision Type1: | Province |
| Subdivision Name1: | Yazd |
| Subdivision Type2: | County |
| Subdivision Name2: | Ardakan |
| Subdivision Type3: | Bakhsh |
| Subdivision Name3: | Kharanaq |
| Subdivision Type4: | Rural District |
| Subdivision Name4: | Robatat |
| Population As Of: | 2006 |
| Population Density Km2: | auto |
| Timezone: | IRST |
| Utc Offset: | +3:30 |
| Timezone Dst: | IRDT |
| Utc Offset Dst: | +4:30 |
Chak Chak or Chek Chek (fa|چکچک|rtl=yes,), also called Chāhak-e Ardakān or Pīr-e Sabz (fa|پیر سبز|label=none|rtl=yes,), is a village in the Yazd Province of Iran. Located near the city of Ardakan, its existence was noted in the 2006 Iranian census, but its population was not reported.
The village consists of a "pir" (a pilgrimage site for Zoroastrians) perched beneath a towering cliff face in the desert of central Iran. It is the most sacred of the mountain shrines of Zoroastrianism, which was formerly the majority and official religion of the Iranian nation. Each year, from 14 to 18 June, thousands of Zoroastrians from Iran and India, among other countries, flock to the site's fire temple.
Among some Zoroastrians, it is believed that Chak Chak is where Nikbanou, the second daughter of the Iranian king Yazdegerd III, was cornered by the Rashidun army in 640 CE, during the Arab conquest of Iran. Fearing that she would be captured, she prayed to Ahura Mazda for protection, prompting the mountain to miraculously open up and provide her with shelter.
Notable features of Chak Chak include the mountain's ever-dripping spring, which are said to be tears of grief that are shed in remembrance of Nikbanou. Growing beside the holy spring is an immense and ancient tree that is said to be Nikbanou's cane. Legend also has it that a petrified colorful cloth from Nikbanou was also visible in the rocks, although pilgrims have since removed it.
The actual temple of Chak Chak is a man-made grotto sheltered by two large bronze doors. The shrine enclosure is floored with marble and its walls are darkened by fires eternally burning in the sanctuary. In the cliffs below the shrine are several roofed pavilions constructed to accommodate pilgrims.