The Blue Lantern Corps was founded by Ganthet and Sayd. two former Guardians of the Universe. For daring to acknowledge the Blackest Night Prophecy, they were banished from Oa. After their exile, Ganthet and Sayd settled on the planet Odym to create the first Blue Power Ring and eventually the Blue Lantern Corps itself.
Ganthet and Sayd started the Blue Lantern Corps, and were then joined by Saint Walker, chosen by Ganthet and Sayd. Protocol in the Blue Lantern Corps has the newest member select the next candidate for the Corps. So, Saint Walker chose Brother Warth, who in turn chose Brother Hymn. Brother Hymn selected Sister Sercy to join, Sister Sercy, being the newest member, will select the next person to join the Blue Lantern Corps.
Recently, after Blackest Night, Ganthet and Sayd are no longer guardians to the Blue Light of Hope.
Saint Walker of Sector 1
Brother Warth of Sector 2
Brother Hynn of Sector 3
Sister Sercy of Sector 4