Origin
In the MLP Episode “Power Ponies” Spike shows Twilight Sparkle a page showing how Mane-iac gained her powers. Mane-iac used to be the power-mad owner of a hair-care product company until she accidentally fell into a vat of green liquid and was electrocuted by a downed power line. The accident gave her a prehensile and stretchable mane and made her crazy. Becoming a super villain Mane-iac is the enemy of the Power Ponies and is considered their “most evil nemesis”.