A hypo gun is a medical device used to do an easy inoculation of a serum or a virus, using a gun- based device with an attached syringe.

In Resident Evil

Resident Evil: The Umbrella Chronicles

Before his encounter with Chris or Jill, Albert Wesker inoculates himself with the prototype virus, given to him by William Birkin, before the Tyrant attack in the mansion laboratory. This gives him super-human strength and speed. This is only shown in Resident Evil: The Umbrella Chronicles.

Resident Evil: Degeneration

Curtis Miller inoculates himself with a hypo gun charged with the G-virus in the Willpharma's Harvardville facility.

Resident Evil 2 / The Darkside Chronicles

Like Curtis Miller, William Birkin inoculates himself with a hypo gun, charged with his only remaining G-virus sample after the gunshot of the U.S.S..

Resident Evil: Operation Raccoon City

According to Inserted Evil, the U.S.S. member known as BERTHA uses a hypo gun in her special abilities. Also, U.S.S. field scientist Four-eyes uses a hypo gun to control the infected creatures, or cause infection to Spec. Ops/turn zombies into V-Acts.

Resident Evil: Dead Aim

Morpheus Duval injects himself the tG-virus in order to heal his fatal wounds caused by Fong Li.

Resident Evil Revelations

Veltro Spokesman injects the tripulation of Queen Zenobia with the T-Abyss Virus, turning them into Oozes.

Resident Evil 4

Saddler and Los Iluminados' Cultists use it in order to infect Leon and Ashley with las Plagas samples.

Resident Evil 5

Jill uses the Hypo Gun to infect a Kijuju native with the Uroboros virus

Further notes

This item will be present in most the games, however it will be first available to the players in Operation Raccoon City as it's BERTHA's most used item in game.