Shimazu Tadahisa (島津忠久; 1179-August 1, 1227) is the first in the line of Shimazu clan.
According to a record of his life, he was reportedly born in Sumiyoshi Taisha in Osaka. He was initially Koremune Tadayoshi (惟宗忠久) but after given Shimazu, Hyuga Province to rule from Minamoto no Yoritomo, he took the name of Shimazu. While there is a story that he was born as a son of Yoritomo, like that of Otomo Yoshinao , it is a story made up afterward to explain the validity of ruling domains. He was ordered to rule over Satsuma Province, Osumi Province, and Hyuga Province.