Ongkharak district
Ongkharak 
    องครักษ์  | |
|---|---|
Buddharupa Shrine (Hor Phra), Faculty of Medicine and Maha Chakri Srinidhorn Medical Centre of Srinakharinwirot University's Ongkharak Campus  | |
District location in Nakhon Nayok province  | |
| Coordinates: 14°7′17″N 101°0′14″E / 14.12139°N 101.00389°E | |
| Country | Thailand | 
| Province | Nakhon Nayok | 
| Area | |
 • Total  | 486.4 km2 (187.8 sq mi) | 
| Population  (2023)  | |
 • Total  | 62,823 | 
| • Density | 129/km2 (330/sq mi) | 
| Time zone | UTC+7 (ICT) | 
| Postal code | 26120  | 
| Calling code | 037 | 
| ISO 3166 code | TH-2604 | 
Ongkharak (Thai: องครักษ์, pronounced [ʔōŋ.kʰā.rák]) is a district (amphoe) in the western part of Nakhon Nayok province, central Thailand.
Once King Chulalongkorn (Rama V) visited Mueang Nakhon Nayok. When he and his company arrived in the area of Ongkharak District, one of the royal guard fell ill and died. The king ordered a shrine built to commemorate his servant. Ongkharak means 'royal guard'.