The RX-78-02 Gundam (RX-78-02 ガンダム?) is the titular mobile suit of the Mobile Suit Gundam: The Origin manga. It also appears briefly in the Mobile Suit Gundam: The Origin OVA and the Mobile Suit Gundam: The Origin Advent of the Red Comet television series, and again in the Mobile Suit Gundam: Cucuruz Doan's Island movie. It was piloted by Amuro Ray during the One Year War.

Its estimate generator output was from 1000kW to 1400kW, its target output was to be at least 150% of the RCX-76.

The operation tests of the RX-78-02, a prototype MS of the Earth Federation, were carried out in secret, but civilian Amuro Ray coincidentally became its pilot when Zeon Forces assaulted Side 7.

The RX-78-02 utilizes its wide array of portable weapons such as its beam rifle and hyper bazooka. It also has fixed weaponry such as two shoulder magnums on the left shoulder, a gatling gun on the right shoulder, and a forearm gatling gun on its left arm. It's also possible to swap a beam saber with an optional armament known as the shoulder cannon.

Furthermore its unable to transform its Beam Sabers to Beam Javelins, its Gundam Hammer doesn't exist, nor does it use the Core Block System until it was upgraded to have one at Jaburo.

As the war progressed to its latter stages, the RX-78-02 was reconfigured into its Late Type/Middle Type form. When the fighting was moved into space a majority of its fixed weapons were removed and swapped with extra thrusters for better mobility and gate shaped armor on the shoulders. Several fixed weapons were removed such as the arm vulcan, the two shoulder magnums, shoulder Gatling gun, and the shoulder cannon not being used more often.