ENIAC

Although Yggdrasilll is relatively recent in the Digimon mythos, a similar character exists in the Digimon Adventure and Digimon Tamers continuities, named ENIAC. ENIAC, as the first computer, laid down the foundations of the Digital World, and because of his unique nature, he exists in multiple universes all at once. ENIAC appears only in the series of games starring Ryo Akiyama for the Wonderswan, and is part of one of Ryo's attempts to defeat the evil Millenniummon. ENIAC's appearance in the game, as a clear orb sitting upon a pedestal, is practically identical to Yggdrasilll's appearance in X-Evolution.

Digimon Tamers Brave Tamer
As Ryo awakens in an unknown Digital World, amnesiac, he finds Monodramon and is introduced to ENIAC, the first computer and system administrator of the digital world. At first, ENIAC just kindly asks for Ryo's help to deal with Millenniummon, but it is soon evident that it knows quite a bit of Ryo's history, as well as being aware of Millenniummon's plans. That being said, he is portrayed as a supportive and benevolent ruler, although not in quite the extent of Norn, as well as an effective strategist and coordinator. He is shown to possess gates that permit travel between different universes, but only uses them to fight Millenniummon's offensive. Ultimately, he is ambushed and deactivated by the VR Digimon. Thus the true first digital computer, the ABC, was found and it revealed that it operated as a sort of shadow system to assist ENIAC, and that neither had created the digital world, but simply reshaped it. However, because it was significantly less powerful, it was unable to resist Millenniummon's attacks for long, and with it's leftover energy sent Ryo through time to fight Millenniummon once and for all. In the end, ENIAC asks Ryo to which world he wanted to return to, and complied with his wishes to go to the Tamers' world, presumably arranging for his parents to join him there.