Leidya infelix is an isopoda parasite present in the waters off the west of Baja California, Mexico.

First described in 2002, by Markham, J. C.[1] The specie's name "infelix" Latin for "ill-fated" or "un-fortunate" was chosen because of the inability to describe this species for close to 90 years.

[2] Leidya infelix is a species known to parasitize Pachygrapsus crassipes.

The head of the female is completely embedded in to the pereon.

They also have dark dorsal splotches on most of their pleomeres.