This article is about the ODST. For the Sabre starfighter, see Echo 4.

Echo Four was the codename for an ODST stationed in Gyeonggi-do, to help test the MJOLNIR Mark VI armor.

Maria-062, the first Spartan to test the armor, was sent in training with several ODSTs. During the armor testing, Spartan-062 hurled a paintball grenade onto the middle of the unsuspecting ODSTs, neutralizing Echos One, Two, Three, Four and Five . The sole survivor of the blast, Echo 6, makes a run for it and was quickly gunned down by 062, but not before initiating the "Bulgoki Gambit." After Maria-062 was subdued and brought back to the Special Operations Center, accompanied by Echo Four and his ODST companions.