Guru Gobind Singh was one of the great gurus (teacher/leaders) of the Sikh religion. A poet, a military leader and a spiritual teacher, he founded the Khalsa, the order of the pure, which is an important part of the Sikh religion. People who are part of the Khalsa are dedicated to resisting oppression and living lives dedicated to the spirit.

http://www.sanatan.org/en/festivals/sikh/gurugobindbirthday.htm