Promachoteuthis sloani is a species of squid from the northern Atlantic Ocean.

[1] P. sloani is characterised by several morphological features: nuchal fusion is absent between the head and mantle, the arms generally bear 3–4 series of suckers, and papillae are present on the tentacles.

[3] The holotype is an immature female of 58 mm mantle length (ML) in near-perfect condition.

The paratype, also an immature female, is larger at 102 mm ML.

Both were trawled in nets that fished to depths greater than 2,650 m.[3]