Lincoln Campbell was an Inhuman Agent of SHIELD and a member of the Secret Warriors. His potential as an Inhuman was discovered by Gordon just as Campbell was struggling with a crippling alcohol problem. He was saved and worked in Afterlife as a transitioner and helped Skye understand the true extent of her Terrigenesis. He originally sided with Jiaying during the Inhumans war with SHIELD, though began to doubt her intentions for Humans upon seeing Jiaying's murder of innocent Agents, and after Skye told him, he helped SHIELD defeat Jiaying, who was revealed to have actually been the monstrous Selene in disguise.
In the aftermath of the conflict, Campbell attempted to start a new peaceful life, but was forced to go into hiding when he was pursued by a murderous Inhuman named Lash and the ATCU, which led him to join SHIELD and become a member of the Secret Warriors. When the ancient and powerful Inhuman, Hive, returned to Earth, his loyalty to SHIELD was brought to a test, as Daisy Johnson was transformed by the dark Inhuman into his evil concubine Black Lady. Campbell, eventually, saved Johnson from Hive's possession with the help of his former enemy, Lash. As the war with Hive reached its conclusion, Campbell sacrificed his life to save Johnson and billions of lives, allowing himself and the dark Inhuman to be destroyed in a nuclear explosion in space.