- For Shimazu Iehisa (1576-1638), first Edo period daimyo of Satsuma, see Shimazu Tadatsune.
- Born: 1547
- Died: 1587
- Sons: Shimazu Toyohisa
- Titles: Nakatsukasa taiyu
- Childhood name: Matashichirô [又七郎]
- Japanese: 島津家久 (Shimazu Iehisa)
Iehisa was the 4th son of Shimazu Takahisa. He was the younger half-brother of Shimazu Shimazu Yoshihisa, lord of the Shimazu clan, and Yoshihiro and Toshihisa. He was one of the most famed Shimazu commanders and fought in numerous battles for Yoshihisa.
In 1575 he went to the Kyoto region to give thanks at the Ise Shrine [伊勢神宮] for the Shimazu's conquest of Satsuma, Ôsumi, and Hyuga and visited the capital, there seeing Oda Nobunaga and his army returning from Osaka and being entertained by Akechi Mitsuhide at Sakamoto. In 1578 he held Taka castle in Hyûga against a powerful Ôtomo army, allowing his brothers time to raise a relief army and rush to his aid. The Ôtomo were crushed at the Battle of Mimigawa, which Iehisa joined by leading his men out of the castle and into the enemy's rear. He especially distinguished himself at the Battle of Okitanawate [沖田畷の戦い], where he led 2,000 Shimazu and 1,000 Arima troops in a victory over Ryûzôji Takanobu that resulted in the latter's death. He fought bravely against the invading Toyotomi forces in 1587 but died suddenly at his Sadowara castle in Hyûga in the 7th month, possibly as the result of poisoning but more probably from illness. He was possibly the finest commander the Shimazu produced in the Sengoku Period.