User blog comment:Ultimatephinferbfan/Alt. Doofenshmirtz Might not be the main villian./@comment-3006892-20110407192001/@comment-2010808-20110412143229

Word of god says alter doof is the bad guy, plus an actually evil doof is very awesome. also, we've heard some song titles, two of which are villain songs, both sung by/about doof.