Red Skull
The Red Skull convinced his now-aware Cosmic Cube, Kobik, to cooperate with S.H.I.E.L.D. in creating Pleasant Hill and discovered that Kobik could alter people's memories to make them believe they had been members of the Hydra of which the Red Skull had told them stories. However, the Red Skull failed to realize that the Hydra he is building and the Hydra Kobik had created false memories of were two different things, with the now-Hydra Captain America disobeying the Red Skull and planning something else.