The RX-78GP03S Gundam "Stamen" (Development codename: Dendrobium Stamen) is a mobile suit that serves as the core unit for the RX-78GP03 Gundam "Dendrobium". It was first seen in Mobile Suit Gundam 0083: Stardust Memory OVA and was piloted by Kou Uraki.

The RX-78GP03S Gundam Stamen is one of two components that make up the RX-78GP03 Gundam "Dendrobium", with the other being the armed base Orchis. The Stamen serves as the control unit for the Gundam "Dendrobium" and can operate on its own when required. The suit has two beam sabers, a folding shield, and a beam rifle as standard armament, and can optionally use folding bazookas. The traditional twin-head Vulcans were removed, with the freed space used to install more advanced avionics and sensor systems.

The "Stamen" was designed with two cockpit options: a Core Block System, and a spherical cockpit with linear seat and panoramic monitors that gives its pilot a full view of the battlefield that was first used in the RX-78NT-1 Gundam "Alex". In the end, the spherical cockpit was selected as the default as it provided superior fire control capabilities. This is of particular importance as when the Stamen is docked with the "Orchis", it must be able to efficiently control and use the large amounts of weapons stored in the "Orchis". Another unique feature of the "Stamen" is the tail binders mounted on the sides of the waist for increased maneuverability and to dock with the Orchis. Lastly, a set of foldable manipulator arms used to retrieve weapons from the Orchis' weapon containers were concealed in the forearms of the GP03S.