Sleeper

The Sleepers are colossal Nazi war machines secretly constructed by the Red Skull during World War II, designed to lie dormant and then activate decades later to unleash destruction. Captain America must race to stop them when they finally awaken.

A creature of Cold War paranoia and Marvel's Silver Age at its most thrillingly imaginative, Sleeper made its mark when it first lurched onto the scene in Captain America #101 in 1968 — sharing those charged pages with Captain America himself, the Red Skull, and a rogues' gallery that reads like a who's who of Marvel's most iconic heroes and villains. With two key issues to its name and a presence that echoes across fifty years of Captain America publishing history, this is a figure whose footprint in the Marvel Universe quietly outpunches its appearance count. For collectors hunting the corners of Cap's world where the stakes feel truly enormous and the Silver Age sense of wonder crackles on every page, Sleeper is exactly the kind of discovery that makes digging through longboxes so rewarding.