Robert "Dr. Stewart" Stewart

Dr. Robert Stewart was a licensed medical doctor and charismatic surgeon with legendary surgical skills. However, he was given the opportunity to become an F-Zero pilot due to the death of his father. In the game F-Zero GX, he is 42. His father, Kevin Stewart, was known to be a scientist and professor. He is also the designer of Dr. Stewart's F-Zero vehicle, the Golden Fox. After Kevin Stewart passed away sometime before the SNES game, Dr. Stewart subsequently retooled his father's Golden Fox and became a pilot in the F-Zero races as well where he raced against the likes of Captain Falcon, Pico, and Samurai Goroh. Allegedly due to uncertainties in timeline, several years after his F-Zero career started, there was a huge accident that injured several pilots. In the aftermath he put his skills as a surgeon to use, and thanks to his skills, none of his patients died. When the new F-Zero X races began, he re-entered the Grand Prix, even though the prize went to Captain Falcon. He re-entered the following year aiming to win the prize. However, he lost to Captain Falcon yet again. In F-Zero GP Legend, Dr. Stewart served as a mentor and physician who joined the Elite Mobile Task Force, next to its leader, Jody Summer. Although a skilled racer, Dr. Stewart very rarely enters the F-Zero races himself, instead preferring to work as a supprt member to the Task Force. He often gives advice to those in need as well as putting his medical skills to the test, especially since he took Jody to a special hospital related to cyborgs, something which he only informed Rick Wheeler of.

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It was later revealed to Dr. Stewart and Jody by Captain Falcon that that the galaxy would meet certain doom by Black Shadow in the 23rd century, unless they awaken Rick from cold sleep in order to combat Dark Million. Zoda was reanimated on account of the savior's coming, and Dr. Stewart was the only one who remained confident in the legend, so revived Rick.

In the GBA game, he was only seen briefly during Jack Levin's, Captain Falcon's and Jody's Story Modes, which are loosely based on the anime, though he wasn't one of the main characters there and could still be an opponent during many of the races. He was the one who assigned Falcon to search for Dr. Clash. (Source: F-Zero Wiki)