Igor

The Kingdom of Malaria's environment is devastated by a mysterious storm. Its king, Malbert, then blackmails the rest of the world to pay the town not to unleash the various doomsday devices invented by its Evil Scientists. They in turn are assisted by Igors, while the kingdom's annual Evil Science Fair showcases the scientists' latest weapons. One Igor, however, who serves the somewhat tedious-minded Doctor Glickenstein, is a talented inventor who aspires to be an Evil Scientist himself. Among his inventions are his friends "Scamper," a re-animated, immortal rabbit with a death wish and "Brain," a unintelligent human brain transplanted into a life support jar.
When the malfunctioning invention explodes and decimates Glickenstein, Igor sees his chance. With Brain and Scamper's help, he assembles a huge, monstrous being from human remains. When he brings her to life, however, he discovers that the "Evil Bone" he gave her was not activated, making her kind, friendly and feminine. Igor tries to convince her that she is evil, inadvertently naming her "Eva", while an attempt to brainwash her into becoming evil by bring her to a brainwashing salon where you're hocked into a machine where your shown monster movies for a couple of hours. Brain also gets the same thing in order to watch TV, but has taken the remote for Eva's room and every time he tries to change the channel the tv in Eva's room changes.
This turns the TV onto the movie Annie and when Eva gets out she can now speak English and has a love for being an actress, so Igor takes her back to the castle to be destroyed in the car. On the way back to the castle Schadenfreude and Jackie try to steal Eva by using a shrink ray to shrink them all but instead get themselves struck. Igor decides to exhibit Eva at the science fair anyway, telling her that the fair is an "Annie" audition.
Igor's nemesis, Dr. Schadenfreude learns of Eva's existence and attempts to steal her, but when that fails, he exposes Igor to King Malbert, who sends Igor to an "Igor Recycling Plant." Schadenfreude activates Eva's Evil Bone and unleashes her into the Science Fair, where she destroys all of the Evil Inventions. Scamper and Brain help Igor escape from the recycling plant and they learn that Malbert had deliberately killed Malaria's crops with a weather ray that made storm clouds so he could implement his "Evil Inventions" plan, thereby keeping himself in power. Rushing into the arena, Igor reasons with Eva to deactivate her Evil Bone and allowing her to regain her sweet personality, while Scamper and Brain deactivate the weather ray which falls and crushes Malbert to death.
Schadenfreude attempts to take power but the citizens revolt upon learning of Malbert's deception. After that Jackie then tries to become the guards new boyfriends, but sees that her voice is cracking so because of this she tries to get another pill only to see that she's all out. After this Jackie's voice continues to become more cracked as we pan up Jackie transforms into a female Igor. The monarchy has been dissolved and Malaria normally becomes a republic, with Igor as president. Schadenfreude is relegated to a pickle salesman, while the annual Science Fair is now an annual musical theater showcase, and Igor and Eva are planning on making a dog, or adopt one.

Question: Who is Igor's nemesis?
Answer: Dr. Schadenfreude