| Vlastimir | |
|---|---|
| archon (ἄρχων) [c] | |
 | |
| Prince of Serbia | |
| Reign | c. 830 – 850 [b] |
| Predecessor | Prosigoj |
| Successor | Mutimir |
| Born | before 805 |
| Died | c. 851 |
| Issue | Mutimir, Strojimir, and Gojnik |
| Dynasty | Vlastimirović |
| Father | Prosigoj |
| Religion | Slavic pagan |
Vlastimir (Serbian Cyrillic: Властимир, Greek: Βλαστίμηρος[a]; c. 805 – 851) was the prince of Serbia from c. 830 until c. 851. Little is known of his reign. He held Serbia during the growing threat posed by the neighbouring, hitherto peaceful, First Bulgarian Empire, which had expanded significantly toward Serbia.
At the time, the Bulgarian Empire and the Byzantine Empire were at peace by treaty, and although the Byzantine Emperor was overlord of the Serb lands, he was unable to aid the Serbs in a potential war. Presian I of Bulgaria eventually invaded Serbia, resulting in a three-year-war, in which the Bulgarian army was devastated and driven out. Vlastimir then turned to the west, expanding well into the hinterland of Dalmatia. He is the eponymous founder of the Vlastimirović dynasty, the first Serbian dynasty.