2nd Dimension Doofenshmirtz is the main villain in the Phineas and Ferb movie Across the 2nd Dimension.
He is an alternate reality version of Dr. Heinz Doofenshmirtz and is far more evil and intelligent. at the also actually succeeds in conquering the Tri-State Area with his vast army of Norm-Bots. After he defeated his nemesis, the alternate-reality Perry the Platypus, he turned him into Platyborg, and he became the general of his robot army.
When he and Doofenshmirtz first meet, the two bonded and even sang a musical number together. This relationship later dims when 2nd Dimension Doofenshmirtz found out that his counterpart was a halfwit, and made fun of him because he could never take over the Tri-State Area in his dimension. He tells Doofenshmirtz that true villainy comes from a tragic backstory. He then tells Doofenshmirtz that he used to own a toy train which he soon lost, though this was clearly was not so tragic compared to Doofenshmirtz's backstory. Later, 2nd Dimension Doofenshmirtz betrays his counterpart and sends him to his doom along with Phineas, Ferb, Perry, and Candace. He also opens a realm to their universe so that he and the Norm-Bots could take over the Tri-State Area that Doofenshmirtz failed to conquer.
Near the end of the movie, Doofenshmirtz found the lost toy train and decided to return it to his evil counterpart. Having reunited with his beloved toy, 2nd Dimension Doofenshmirtz took back all his wicked schemes and destroyed his Norm-Bots with a self-destruct button. He then departs back to his own dimension, only to be arrested and imprisoned for his crimes against humanity.