Shinji Ikari -- The third suitable person selected by the
Marduke agency. Without training, he managed to start up
Eva-01, which had been ridiculed as an "09" (oh
nein) system because of its low start-up probability of 0.000000001
%, thus surprising all those involved. Thereafter, he remained in
Tokyo-3 as the dedicated pilot of
Eva-01. Having a higher
synchronization ratio than the other
Children, he often became the core force in battles against
Angels.
Source: The End of Evangelion : Glossary contained within The End of Evangelion - Theatrical Program.
The use of “Children” in the titles the First Children, Second Children, Third Children, is not a mistake. It should not be First Child, Second Child, Third Child; the use of “Child” is incorrect (no matter what AD Vision tries to tell you). GAINAX chose to use the English word “Children” as the identifier of the Evangelion pilots, it is not a translation mistake, it was intentional.