| Type: | monarch |
| Sithu စည်သူ | |
| Reign: | 1 September 1340 – 29 March 1344 |
| Succession: | Regent of Pinya |
| Predecessor: | Uzana I of Pinya |
| Successor: | Kyawswa I |
| Suc-Type: | Successor |
| Succession1: | Viceroy of Myinsaing |
| Reign1: | – 29 March 1344 |
| Predecessor1: | Yazathingyan |
| Successor1: | Shwe Nan Shin |
| Spouse: | Saw Htut |
| Issue: | Saw Gyi (daughter) Saw Einthe (daughter) |
| House: | Myinsaing |
| Father: | Narathihapate |
| Mother: | Shin Shwe |
| Birth Date: | early 1280s |
| Birth Place: | Pagan (Bagan) |
| Death Date: | 1344 |
| Death Place: | Pinya |
| Religion: | Theravada Buddhism |
Sithu of Pinya (Burmese: စည်သူ, in Burmese pronounced as /sìðù/; also known as Myinsaing Sithu) was regent of Pinya from 1340 to 1344.[1] He is not mentioned in any of the royal chronicles. He only appears in a Pinya era inscription as "King" Myinsaing Sithu. Sithu, who according to the inscription succeeded Uzana I, may have been a caretaker for his nephew and son-in-law Kyawswa I of Pinya. Sithu's elder daughter Saw Gyi was married to Kyawswa I.[1] At least one contemporary inscription donated by Kyawswa I's chief consort on 17 June 1342 disputes Sithu's claim, saying that Kyawswa I was already king.[2]
The king was likely Kyawswa I's maternal uncle since Kyawswa I's father Thihathu had only two brothers, Athinkhaya and Yazathingyan, both of whom had already died.