Knights of the Round Table

The Knights of the Round Table are the lieutenants of King Arthur in Sonic and the Black Knight. Much to Sonic's surprise, all of these knights are alternate reality doppelgangers of his companions from previous adventures; namely: Also:
 * Sir Lancelot, Knight of the Lake - an alternate version of Shadow the Hedgehog
 * Sir Galahad, Knight of the Sun - an alternate version of Knuckles the Echidna
 * Sir Percival, Knight of the Grail - an alternate version of Blaze the Cat
 * Sir Galahad (does not appear in the game storyline; multiplayer only) - an alternate version of Silver the Hedgehog
 * Sir Lamorak (does not appear in the game storyline; multiplayer only) - an alternate version of Jet the Hawk
 * King Arthur - technically a Knight of the Round Table himself, as attested by Caliburn during the battle on Faraway Avalon
 * Sir Sonic, "Knight of the Wind" - potentially, given the title bestowed upon him at the very end of the game

Sonic and the Black Knight
Sir Lancelot, Sir Galahad, and Sir Percival are tasked by King Arthur to track down Sonic and Merlina during Sonic and the Black Knight's opening sequence. While Galahad and Percival express their misgivings, the Knights of the Round Table nonetheless obey, and pursue Sonic across the Grand Kingdom and beyond. Sir Lancelot is fought in Deep Woods; Sir Galahad upon Titanic Plain, and Sir Percival in Molten Mine.

Despite suffering humiliating defeats at the hands of Sonic and Caliburn, the Knights do not give up. While Sonic battles King Arthur on the island of Avalon, Lancelot, Galahad, and Percival manage to track down Merlina the Sorceress in Camelot Castle. The Blue Blur arrives just in time to see Merlina reveal herself as the true villain of Sonic and the Black Knight: the Dark Queen. As the castle falls apart around them, Sonic and the Knights flee through Knight's Passage. In order to save the Kingdom, the former lieutenants of King Arthur agree to work with Sonic and Nimue to halt the Dark Queen's magic by activating four sacred stones. Sir Lancelot rushes to Shrouded Forest, Sir Galahad to Great Megalith, Sir Percival to The Cauldron, and Sonic to Dragon's Lair.

Real-world mythology
Obviously, Sonic and the Black Knight's Knights of the Round Table are based on the traditional English legends of King Arthur and Camelot. However, the precise degree to which the real-world Arthurian legends should be considered canonical to SatBK's backstory is unknown. Nevertheless; a quick guide to the mythos and geneology of the IRL version: