He is voiced by the late Bill Scott in Season 1, the late Roger C. Carmel in Season 2, and Brian Cummings in Season 3 onwards.
Not much is known how he earned the position of the highest ranking knight in King Gregor's court, but it may be possible that he earned it after Duke Igthorn betrayed the King.
Sir Tuxford is a loyal, highly disciplined knight. He takes his job seriously and makes sure his squires and pages (e.g. Cavin) do the same. He acts somewhat like a father figure towards Cavin, often punishing him for breaking rules and rewarding him for acts of bravery.
Cavin, one of the main protagonists of the cartoon, is a page under Sir Tuxford, because of this, he acts as both the voice of reason and a fatherly figure towards the young page (Cavin's parents are never mentioned in the series).
In the series premiere "A New Beginning", Sir Tuxford has tasked his squire Unwin and his page Cavin to deliver supplies to a group of woodsmen that have made a camp near where Duke Igthorn has stationed his troops and a catapult that he plans on using to destroy Castle Dunwyn. They are soon caught off-guard by some of Igthorn's ogres, causing all of them to flee from the camp. Cavin eventually discovers the Gummi Bears and with their help, he is able to stop Igthorn's plans and destroy the catapult. Sir Tuxford is seen amongst the Dunwynian citizens congratulating Cavin for saving the kingdom.
In "Up, Up, & Away", Sir Tuxford is informed by Unwin that Cavin was caught stealing from the royal storage room. Sir Tuxford demotes Cavin to kitchen duty as a result, telling him "A thief will never make a knight." He however reverses this action after witnessing Cavin rescue Princess Calla after she was kidnapped by Duke Igthorn, restoring him back to full status as page once more.
In "Ogre for a Day", Cavin accidentally trips Sir Tuxford and his knights with a tripwire he meant to use against Igthorn's ogres. Enraged by his childish behavior and failure to capture the ogres, he informs Cavin about his disruptive behavior to which King Gregor lectures Cavin and tells him that his actions will "never make him a knight", despite this, he does not demote Cavin like in "Up, Up, and Away". At the end of the episode, he is seen standing alongside King Gregor, Princess Calla, and his page Cavin after the latter rescues King Gregor from an attempted kidnapping of the King to convince him to give up his kingdom. He is astonished, but pleased after witnessing Cavin receiving a kiss from Princess Calla.
Sir Tuxford's biggest role comes in the episode "Tuxford's Turnaround". Here, Sir Tuxford begins preforming his duties poorly, causing Cavin and other bystanders to think he's losing his touch as a knight. However, he later reverses this belief and resumes his role as the head knight of Dunwyn afterwards.
In the two-part series finale "King Igthorn", Sir Tuxford, as well as the rest of his knights and King Gregor are overrun and defeated by Duke Igthorn and his ogres. As a result, King Gregor is overthrown and, alongside Sir Tuxford, Princess Calla, and the rest of the knights are imprisoned. All of them are freed however when Cavin and the Gummi Bears lead a rebellion against Igthorn. Sir Tuxford is last seen fight off against Igthorn's remaining troops.