Maduin and Madeen don't bear much resemblance across incarnations. In FF6, he is Terra's father as a character and looks like a strange knight; as a summon, he gives non-elemental damage on all enemies. In FF9, he masquerades as Eiko's moogle companion and dishes out Holy damage as her most powerful summon. He also shows up in FFTA. See also FF6 Characters.
FF6 -Maduin ATK: Chaos Wing | |
FF9 -Madeen ATK: Terra Homing | |
Tactics Advance -Madeen ATK: Not named |