OK - the above makes Gendou sound vaguely normal.

Gendou Ikari was a normal chapie up until somewhere around 2005, when his wife Yui died (or alternatively was absorbed by Unit 01) during an early Evangelion activation test. Shinji was sent away from home by his father - in many ways to protect him from Nerv and his father.

After this, Gendou turned in on himself, and became a hard-edged man that no-one could touch, someone who would use anyone and anything to achieve his goals. Even his son. Even his world.

Gendou is in charge of Nerv - the top secret UN organisation that is meant to be the last line of defense against the Angel. The primary weapon for use against them was created by Project E - the Evangelions. These are fearsome creatures that are man's best attempt at building an Angel.

However, this is just a cover up story - Nerv and all of the technical might of Eva is just a cover story for the Human Instrumentality Project. The HIP is being run by Gendou Ikari for Seele, the committee overseeing Nerv. Gendou, however, is merely using Seele and the HIP to achieve his goals - returning his lost love Yui to him.
The pawns in this game from Gendou's point of view are Nerv, Seele, Shinji (his son), Rei Ayanami, and Dr Ritsuko Akagi. There are many more (Kaji, Misato Katsuraga, Asuka Langley Soryu, etc...) but they are all sub points - minor items to manipulate, and if needed, to deal with.