Hoffan

Hoffans are a race of humans from the planet hoff, A planet visited by the Atlantis Expedition during their first years in the Pegasus Galaxy.

When Atlantis 1 visited the Hoffans, they were at first shown around the city, until the leader of the Hoffans informed them about the cure against the Wraith feeding they were working on. The Atlantis Expedition decided to help them and with the help of Dr. Carson Beckett they were able to complete the cure and tested it on the Wraith which the Atlantis Expedition had captured earlier. It however turned out that not only did the vaccine kill the Wraith who fed on a person using the substance, but that it also only worked on 50% of the people which were using it, while the other half died. Nevertheless the Hoffans decided to use it despite Atlantis 1 warning them that the Wraith won't let them live with such a cure. (ATL: "Poisoning the Well")

It later turned out that the Atlantis Expedition was right since the Wraith killed the entire Hoffan population after they found out about the vaccine. (ATL: "The Kindred, Part 1")