A Parallel World Counterpart is a near-exact copy of a person living in a world parallel to their own. Each and every person has a counterpart in a parallel world. This person is extremely similar to their counterpart, both in appearance and personality. It is highly possible that if a person falls in love with another, their counterpart will fall in love with the other person's counterpart. This is backed by the fact that a person who is born will take their parent's genes, and get the genes to make them a counterpart, they would need to have parents who were counterparts to their own counterpart's parents.
When one passes through the Gate, their soul is transferred into their counterpart's body, and is only known to return if their counterpart dies. If a person travels through the gate and their counterpart is dead, the person's whole body will enter the parallel world. This concept is exclusive to the 2003 anime.
- Edward Elric - Edward (last name unknown, though it is possible his last name is Heiderich if he and Alfons Heidrerich are brothers like Edward and Alphonse Elric. Whether or not they actually are kin is unknown).
- Alphonse Elric - Alfons Heiderich
- Rosé Thomas - Noah
- King Bradley - Fritz Lang
- Maes Hughes - Officer Hughes
- Gracia Hughes - Gracia
- Dante - (possibly) Dietlinde Eckhart
- Lust - unnamed counterpart
- Scar - unnamed truck driver
- Lyra - unnamed waitress
- Bido, Roa, and Dolcetto - unnamed rocket scientists working with Alfons
- Frank Archer - Erik Jan Hanussen