The PMX-003 The-O is a mobile suit from the series Mobile Suit Zeta Gundam and is piloted by Paptimus Scirocco.

The fourth of five mobile suits built by the Newtype Paptimus Scirocco on the Jupitris, the PMX-003 The-O is Scirocco’s personal mobile suit, and perhaps the most powerful. It has an independently developed control system to take advantage of his rare spatial recognition abilities, and its control interface is specifically tuned for Scirocco's use, making The-O impossible to pilot except by Scirocco himself. The generator output specifications are modest at less than 2,000Kw; however, The-O is equipped with a large-scale thermonuclear reactor comparable to that of a warship.

The-O has very thick armor that can withstand direct beam hits, such as from the AMX-004 Qubeley's funnels. Although very bulky and heavy, it is outfitted with enough thrusters to maneuver and move at very high speeds, demonstrating powerful thrust similar to mobile armors. It is also extremely agile despite its massive frame, with performance that greatly surpasses common MS and displaying tremendous space combat capabilities. By taking advantage of The-O's large size, it is possible to load large amounts of propellant into various parts of the body and the skirt armor to extend operation time. The leg and armor units incorporate a complex multi-joint structure that allow a high degree of freedom of movement. These parts significantly differ from those found in typical mobile suits.

In terms of weapons, The-O is only equipped with four beam swords and a beam rifle. However, thanks to its unique sub-arms, The-O can wield all four swords at once, something that no other mobile suit could do, allowing The-O to excel at close quarters combat. The-O is a robust machine designed with emphasis on mobility instead of excessive firepower, and features an excellent interface that reflects the skill of the pilot.

The last special feature of The-O is the Bio-Sensor (no relation to the device installed in the MSZ-006 Zeta Gundam), which functions like a psycommu system and allows Scirocco to more easily interface with his suit.