Abstract: A microelectronic device includes a stack structure comprising a vertically alternating sequence of insulative structures and conductive structures arranged in tiers and the tiers arranged in decks. At least one live pillar, comprising a channel material, extends through the decks to a source/drain region. At least one source/drain contact also extends through the decks. In a transition area horizontally between the live pillar(s) and the source/drain contact(s), at least one dummy pillar extends through at least one of the decks. The dummy pillar(s) are separated from the source/drain region by at least one of the tiers of a lower of the decks. The dummy pillar(s) are also spaced from the source/drain contact(s). Additional microelectronic devices are also disclosed, as are related methods and electronic systems.