Scerdilaidas or Skerdilaid (; ruled 218206 BC) was an Illyrian ruler of the Illyrian kingdom under the Labeatan dynasty. Before taking the throne, Scerdilaidas was commander of the Illyrian armies and played a major role in the Illyrian Wars against the Romans. Scerdilaidas was one of the youngest brothers of Agron and father of Pleuratus III and grandfather of Gentius. Scerdilaidas took part in many expeditions in the Ionian and Aegean with Demetrius and his brother-in-law Amynas of Athamania. During his early reign Scerdilaidas was an ally of Rome. In 217 BC Scerdilaidas later adopted Roman rule and became an enemy of Macedonia for parleying with Rome. With the Romans invested by Hannibal, Philip V of Macedon sought to take southern Illyria from Scerdilaidas and made several advancements into the Ardiaean State from 214 BC to 210 BC. In reaction, the Aetolian League and the Dardanians under Longarus joined with Scerdilaidas to defeat the Macedonians in 208 BC. With no chance of victory, Philip V accepted peace in 205 BC. Unlike most other Illyrian kings of which there is only sparse data, Scerdilaidas is mentioned in the writings of the historian Appian, Livy and Polybius, and in their chronicles of the Roman and Greek wars. Commander Under Queen Teuta Long before he became king, Scerdilaidas was a leader who helped determine Illyrian policy. He was the commander of the Illyrian army during the reign of his brother, Agron. Scerdilaidas also served under Teuta and even Demetrius of Pharos. He was one of the leading supporters of Queen Teuta when she took on the regency of Pinnes. He played a determining role in the plans of Teuta to create an Adriatic front against Rome. Under the reign of Teuta, Scerdilaidas was the commander of a large land force of 5,000 during the Invasion of Epirus in 230 BC. Scerdilaidas marched south through the pass at Antigoneia to assist Teuta's forces at the Epirote capital of Phoenice. News that Scerdilaidas was on his way caused the Epirotes to send part of their forces north to secure the city. After the Illyrian victory at the Battle of Phoenice, Epirus begged for assistance from the Greek Leagues, while Teuta's army, having joined up with the forces led by Scerdilaidas, marched inland to Halicranum deep in the heart of Epirus, on the plain of modern Ioannina. Scerdilaidas chose a good position and prepared the army