Logan Walker is the main protagonist of Call of Duty: Ghosts.
He is a member of Ghosts that inherited his father, Elias', Ghost Mask. He was originally a Sergeant of the U.S. Army before being welcomed into the Ghosts by his father. He's also the younger brother of fellow Ghost, David "Hesh" Walker, who he, in fact, always followed when he was younger (as said by Elias in a Rorke File; he, Logan, and Hesh was walking along the Pacific once and Elias only seen two sets of footprints as Logan was LITERALLY walking in Hesh's footsteps).
The fourth lead COD Era character, others being John Price of Modern Warfare, Alex Mason of History Era Black Ops, and Commander Mason of Future Era Black Ops.