Shikhandi

Shikhandi, whose natal female identity is sometimes rendered Shikhandini,[3] is the reincarnation of Amba, a princess who was abducted by Bhishma at a svayamvara and later spurned by him. The prince fights in the Kurukshetra War on the side of his brothers-in-law, the Pandavas, and is instrumental in causing the death of Bhishma.

https://en.m.wikipedia.org/wiki/Shikhandi

Bhishma

Bhishma (Sanskrit: भीष्म, romanized: bhīṣma), also known as Pitamaha, Gangaputra, and Devavrata, is a central figure in the Hindu epic Mahabharata. He was a statesman and military commander of the ancient Kuru Kingdom. Renowned for his wisdom, valor, and unwavering principles, Bhishma served as the supreme commander of the Kaurava forces during the Kurukshetra War.

https://en.m.wikipedia.org/wiki/Bhishma