The Ancient Spirits of Evil are being of supreme evil power.  They have exsisted since the beginning itself and can never be destroyed.  They cannot directly act in "universal" affairs, so they direct their powers through stone statues into servants that do their bidding for them.  They live only to destroy good and rule all.  In some universes, all people know them as "GODS", while in others, they are known as "DEMONS".  There archenemies, The Ancient Spirits of Good, are exactly identical to them.  They both are four creatures with immense power who use others to do there bidding, but the name gives away the difference.

    With Mumm-Ra failing to destroy the Thundercats, The Ancient Spirits of Evil decided that it was time once and for all to end the bitter war and have all their followers and allies destroy the good in the universe.  With their unlimited powers, they summoned warriors from across time and space, and brought some back from the dead, upgrading each member of the Alliance with new powers and abilities.  Now, they are ready for the final battle to begin.