Dark Power (闇の力 Yami no Chikara) is an evil and powerful energy in the Mega Man Battle Network series that is created with negative emotions, such as hatred, and can't be destroyed as long as negative emotions exist. It is mainly used by Nebula and the Darkloids to increase their power, and spreads it with Dark Chips to taint NetNavis, creating Dark Souls that inhabit the Dark World.
Later in Mega Man Battle Network 5, Dark Power is present in all Liberation Missions. Chaos Unison is the result of Dark Power. The Dark Chip Factory contains Dark Power in great amounts, and Nebula Gray is mainly made of Dark Power, which is used on Dark Chips. The Nebula Area (Murkland) also contains Dark Power, which gives power to the Chaos Lord.