Evangelion Unit-01 (エヴァンゲリオン初号機[?], "Evangerion Shogōki") is the first non-prototype Evangelion unit, and is referred to as the "EVA-01 TEST TYPE". It houses the soul of Shinji's mother, Yui Ikari. It is mainly piloted by Shinji Ikari. Unit-01 serves as the flagship model for the series.

Evangelion Unit-01 is, like all Evangelions, a giant artificial human (Jinzo ningen[?]) with brown skin. It has a mouth similar to that of a human as well as two round green eyes. The face also has four small nostrils and red blood. Its true appearance is concealed under armor, called Type-B Gear, also serving to limit its real strength. The Unit-01 armor is a prototype model, and therefore different from the following models. This consists of two blueish large plates covering the pectorals, as well as three triangular pieces on the abdomen up to the crotch. The armor is predominantly purple with green stripes on the arms and details in black. Its gorget is made up of several pieces of yellowish/orange color. Its most characteristic element is undoubtedly its helmet, unique for each Eva, with its prominent horn and its "collar", vaguely evoking that of a single horn oni.

The armor also adds several other elements necessary for combat and piloting. First, there is the system to accommodate the Entry Plug and the umbilical cable in the back of the Evangelion below the neck. For combat, the armor has shoulder pylons that can be open to store and remove the progressive knife.