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Pachycereus is a genus of large cacti native to Central America and Mexico.

[1] They form large shrubs or small trees up to 15 m tall, with stout stems up to 1 m in diameter.

Pachycereus comes from the ancient Greek παχύς (pachys) meaning "thick" and the Latin cereus meaning "torch".

As of February 2025[update], Plants of the World Online accepted six species:[1] P. pringlei is the tallest cactus species in the world, with a maximum recorded height of 19.2 m.[2] These genera have been brought into synonymy with Pachycereus by some sources,[citation needed] although as of October 2023[update], not by Plants of the World Online:[1] Species that may be placed in Pachycereus include: