Saint Stefan Uroš V (Serbian: Свети Стефан Урош V; 1336 – 2/4 December 1371), known in historiography as Uroš the Weak (Урош Нејаки/Uroš Nejaki), was king of the Serbian Empire (1346–1355) as co-regent of his father Stefan Uroš IV Dušan Silni ("The Mighty") and then Emperor (tsar) (1355–1371).

Stefan Uroš V was the only son of Stefan Uroš IV Dušan by Helena of Bulgaria, the sister of Ivan Alexander of Bulgaria. He had been crowned as king (second highest title) in the capacity of heir and co-ruler after Dušan was crowned emperor in 1346. Although by the time of his succession as sole ruler and emperor in 1355 Stefan Uroš V was no longer a minor, he remained heavily dependent on his mother and various members of the court.

The account of the contemporary John VI Kantakouzenos describes a descent of the Serbian Empire into civil war on death of Uroš' father and his accession. However, Kantakouzenos wrote about the Greek lands rather than the Serbian core lands. Further the general disorder long with the powerlessness of the center represents the situation that arose much later in Uroš's reign. According to Mihaljčić, during the initial years of his rule the threats to the territorial integrity of Uroš's empire came not from not internal dissension but external attacks.

The death of Uroš's father was quickly followed by the death of Preljub, who ruled Thessaly. In the spring of 1356, Nikephoros Orsini landed a force on the coast of Thessaly and quickly overran it. He then followed up this success by driving Simeon Uroš from Arcania. Simeon responded to his expulsion by seizing Kostur and proclaiming himself Tsar in opposition to Uroš, but the support he gained was limited. The Sabor (council) held in Skoplje did not accept Simeon's claims and following the Sabor, Uroš was energetic in his political activities, publishing a number of charters. Simeon in 1358 attacked in the Skadar region, but was defeated.

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