Rapicactus is a genus of cactus in the tribe Cacteae, subfamily Cactoideae.

It has been synonymized with Turbinicarpus but molecular phylogenetic studies have supported its monophyly and separation from that genus.

[2] It was characterized by having thick roots with a constriction above forming a neck.

The circumscription of Turbinicarpus has been described as "remarkably unstable", with species regularly transferred to other genera.

[1] The broad circumscription of Turbinicarpus was recognized as polyphyletic by Hunt in 2016.