Dr. Mordin Solus is a master geneticist and former operative for the salarian Special Tasks Group. Dr. Solus is well known for his work in perpetuating the genophage, a biological weapon that almost completely sterilized the krogan species. He eventually left the STG to open a clinic on Omega, where his combat skills kept the clinic safe and operational amid Omega's lawless society.
In 2185, Commander Shepard recruited Dr. Solus to research the Collectors and the Reapers. He was a member of the Normandy crew that traveled beyond the Omega 4 relay to attack the Collectors. He survived the mission, but his current whereabouts are unknown.