Gennai

Gennai is a mysterous being which the Digi-Destined encounter after the battle with Devimon. Gennai comes to the first Digi-Destined as an old man but in the second series he is shown as and comes to the new Digi-Destined as a very young person guarding the the Digi-Eggs from Piedmon and the other Dark Masters; Gennai claims to have been there at the start of the Digital World.

His young-self was voiced by Hiroaki Hirata(Japan) & Jeff Nimoy (English) while his old self voiced by Joji Yanami (Japan) & Michael Reynolds (English).