Gennady has a striking similarity to Kennedy, which is a popular unisex name in the U.S. Gennady, alternatively spelled Gennadiy, Gennadi, and Genndy, and Геннадий in Russian. This Russian boy's name comes from Gennadius, the name from Greek gennados, meaning "noble, generous." In Bulgarian and Georgian the name is spelled Genadi, while it is Ghenadie in Romanian. None of these are used in the U.S.
Saint Gennadius was a martyr from Constantinople, the 21st Ecumenical Patriarch of that ancient city. He was born around the same time as Gennadius of Marseilles, the 5th century priest and historian who was called Gennadius Scholasticus. Perhaps ironically, there was later a man known as Gennadius Scholarius who was a Byzantine theologian and philosopher. There was also 7th century Gennadius II, a Byzantine general. In the 400's there was politician Gennadius Avienus. In the 9th century there was a Bishop named Gennadius of Astorga.
Genndy Tartacovsky was the animator of 90's hit cartoons The Powerpuff Girls and Dexter's Lab, and he directed the Hotel Transylvania series. Gennady Karponosov was an Olympic champion, Gennady/Gennadius of Novgorod was an Archbishop between 1484 and 1504, and Gennady Padalka was a Russian cosmonaut.
Gennadius is a genus of moth.