Daruk is one of the main character in The Legend of Zelda: Breath of the Wild. He is a Goron warrior and the chosen Champion of his people and as such he is one of Link's allies 100 years before the events of Breath of the Wild, and wears the same blue scarf as Revali, Urbosa, Princess Mipha, Link and Zelda. Daruk is able to create a magic shield to protect himself. Yunobo who is descended from Daruk also possess this quirk, meaning it is a hereditary ability.
For the moment Daruk's role in the Zelda series is only composed of informations with an unconfirmed timeline placement and should stay this way until we have a definitive answer, so please don't add any information regarding the timeline placement without OFFICIAL confirmation, thanks.
100 years before The Legend of Zelda: Breath of the Wild
Daruk was chosen by King Rhoam Bosphoramus Hyrule and Princess Zelda due to his unique ability to become the Goron Champion and the pilot of the Divine Beast Vah Rudania as a protector of Hyrule in line with their plan to prentively build an army in hope of destroying Ganon the moment he would return, initially Daruk struggled to control his Divine Beast, but eventually was able to utilize it properly. Unfortunately, he was ambushed and killed by Fireblight Ganon.His spirit was then trapped within the Divine Beast.
The Legend of Zelda: Breath of the Wild
During Breath of the Wild, Daruk's spirit was freed by Link a century after his demise when the Hero slew Fireblight Ganon, Daruk gives Link Daruk's Protection as a mean to thanks him. When Link finally faced the monster, he along with the other Champions fired a large laser beam in order to weaken Ganon allowing Link to destroy the physical form of the beast.