He is an alien member of the galactic Blue Lantern Corps, an organization dedicated to spreading peace and harmony through the power of hope.

Despite Astonia's sun dying, Walker calms his people and gives them hope, leading to him being inducted into the Blue Lantern Corps.

[3] Saint Walker and his fellow Blue Lanterns are introduced during Final Crisis as part of the build-up to Blackest Night.

2) #55 (2011), Saint Walker joins the titular team in battling Eclipso, and attempts to assist the resurrected Hank Henshaw against Doomsday on Batman's orders.

[5] In War of the Green Lanterns, Saint Walker is trapped inside the Book of the Black before being freed by Kyle Rayner.