Heteroplacidium compactum is a species of areolate, crustose lichen in the family Verrucariaceae.

It is a lichenicolous lichen, growing as a facultative parasite on other lichens, typically on non-calcareous rock.

[2] Heteroplacidium zamenhofianum is a closely related species distinguished by having perithecia situated in the algal layer, and smaller ascospores (14–16 by 6–7 μm) with a more narrow ellipsoid shape.

[3] The lichen was originally described in 1857 by Italian lichenologist Abramo Bartolommeo Massalongo as Placidium compactum.

After having been shuffled to various genera in its taxonomic history,[1] it was transferred to Heteroplacidium in 2008 following molecular phylogenetic analysis of that genus.