O-negative
O-negative was a Human blood type. 

This blood type was one of the three remaining blood types (the others being B-negative and AB-positive)  was required to get for Damron in order for the Xindi-Reptilian to synthesize a virus for their bio-weapon, which required samples of all eight types of Human blood to be properly calibrated. Detroit prostitute Georgia Tandy had a blood type of O-negative. After Damron delivered Tandy, he requested to be paid his bounty, but was told he wouldn't be paid until they received that remaining two blood types. ()

After being changed into a Solid, specifically a Human, by the Great Link in 2372, Doctor Julian Bashir noted that Odo's blood type was O-negative. ()

Physiology