Otacon (オタコン, Otacon), whose real name is Hal Emmerich (ハル・エメリッヒ, Hal Emmerich), is a character from the Metal Gear series who makes his first appearance in Metal Gear Solid.
Otacon is the one who helped design Metal Gear REX, a bipedal tank capable of launching nuclear missiles from any terrain, unaware of its true purpose. Feeling guilty about his involvement, he assists Snake in dissembling Metal Gear REX. If the player submits to Ocelot's torture in MGS, he is the one who will escape with the player at the end instead of Meryl.
He returns in Metal Gear Solid 2: Sons of Liberty as part of the Philanthropy group, an anti-Metal Gear organization.
Main article: Codec Conversations
Otacon appears in Shadow Moses Island and contacts Snake via Codec and informs about the fighters in the battlefield if a down taunt is inputted quickly, resulting in a Smash taunt. Otacon informs Snake about Donkey Kong, Diddy Kong, Link, Samus, Yoshi, Kirby, Captain Falcon, Mr. Game & Watch, Pit, Ganondorf, Sonic and R.O.B. If Snake gets KO'ed while Otacon is on the communication line, he says the infamous line: "Snake? Snake? Snaaaakkkkeee!"
Main article: List of spirits (Metal Gear series)
Otacon, under his real name Hal Emmerich, appears as a Spirit in Ultimate, represented by his look in Metal Gear Solid 4: Guns of the Patriots. In his Spirit Battle, he is represented by Dr. Mario.