Yūki Hideyasu (結城 秀康, 1 March 1574 – 2 June 1607) was a Japanese samurai who lived during the Azuchi–Momoyama and early Edo periods.

When Oman became pregnant, Ieyasu feared his wife's wrath, so he sheltered the girl in the home of his retainer Honda Shigetsugu, in Ofumi Village near Hamamatsu Castle, and it was there that Ogimaru and his brother were born.

It was not until age three that he met Ieyasu, and even that meeting, cold as it was, was not arranged by the father, but instead by Ogimaru's elder half-brother, Matsudaira Nobuyasu.

After Oda Nobunaga demanded that Ieyasu order Nobuyasu's seppuku, Ogimaru would have been the next in line to inherit the Tokugawa headship by birth; however, as part of the peace negotiations following the Battle of Komaki-Nagakute, he was given in adoption (in reality as a hostage) to the childless Hashiba Hideyoshi in 1584.

Professor Sunao Kawaguchi suspected the reason Hideyasu was not appointed as successor of Ieyasu as Shogun was because he spent most of his life close to the house of Toyotomi clan.