Master of the Order/Legends

Master of the Order was a title used to denote the highest-ranking member of the Jedi High Council during the last decades of the Old Republic. It was separate from the title of Grand Master, which was used to denote the leader of the entire Order, rather than just the High Council.

History
Jedi Master Mace Windu held the title until after the Battle of Geonosis. After he joined the rest of the Order in military positions during the Clone Wars, he gave the title to Jedi Grand Master Yoda, who remained on Coruscant to serve as Chancellor Palpatine's chief military adviser.

Known Masters of the Order

 * Mace Windu (—22 BBY)
 * Yoda (22 BBY—19 BBY)

Behind the scenes
The title "Master of the Order" first appeared in The Complete Star Wars Encyclopedia, but it is unclear if this was meant to be a separate title or another term for Grand Master.