Humanoid Interface (宇宙人, uchuu-jin, literally "space person", commonly used to refer to an extraterrestrial alien) refers to a number of data organisms that are created by either the Data Overmind or the Sky Canopy Dominion.
Except for Yuki Nagato, Kyon considers them "monsters" and inhuman.
The versions of Humanoid Interface created by the Data Overmind are capable of mimicking certain human functions (such as eating, bleeding, breathing, communicating, etc.). Humanoid Interfaces have varying degrees of success in comprehending human emotions. Yuki Nagato demonstrates considerable understanding of and sympathy for human emotions, but has difficulty expressing them. In a reverse of this, Ryoko Asakura readily parrots a variety of emotions, but lacks genuine understanding of human feelings. Emiri Kimidori has not demonstrated any communication problems and even acted as a "chaperone" for Yuki after The Disappearance. These interfaces were originally created to observe Haruhi Suzumiya and communicate through verbal language, an ability that the Data Overmind lacks. Due their nature as data life forms they possess the ability to manipulate data, allowing them to alter reality. Without a connection to the Data Overmind, they can become "ill" and their powers are greatly reduced.
These versions are referred to as "TFEIs" by the 'Agency'.
Canopy Dominion Interfaces
A second form of Humanoid Interfaces was created by the Sky Canopy Dominion. So far only one has been seen and it seems to have less communicative ability than the Humanoid Interfaces created by the Data Overmind. The one seen, Kuyou Suou, seems to have limited to no awareness of her surroundings, poor social skills, and virtually no communication skills. Like the Humanoid Interfaces from the Data Overmind, she can manipulate data, although in a different manner than the TFEIs.
They appear to have been designed to communicate with TFEIs more than with humans. Establishing contact with a TFEI weakens the latter's connection to the Data Overmind, causing an apparent "illness". The Data Overmind believed this data transfer was valuable, but Kuyou Suou felt the communication achieved little or nothing.
Data Overmind Interfaces
Humanoid interfaces in general have displayed superior strength, stamina and speed, as well as superhuman senses. They have demonstrated data-altering abilities (where the data is reality; they can change but not create data, extending to probability manipulation) which sometimes require incantations which sounds like high-speed speech (Kyon has referred to this as "bogus magic"). They have cross-temporal synchronization abilities (the ability to share information with previous and future versions of themselves) and the ability to create, repair or enter a data jurisdiction space and completely control objects within, including making attacks within it. When cut off from the Data Overmind, their powers are severely limited, resulting in "illness".
Humanoid Interfaces also have an Emergency_MODE function that lets them access virtually limitless other powers, but this mode is "seldom activated... unless necessary." Known applications of the Emergency_MODE include stopping time in a designated area, stopping Haruhi's powers from altering data, and creating a correction program that can repair any potential damage to Space-Time, even to the extent of returning Haruhi's powers to her after they have all been used up.