Egg Fu

Egg Fu is an example of a character that you would think won't come back, but still does.
Pre-Crisis

Racism taken to illogical extremes

Egg Fu was a Wonder Woman enemy that embodied nearly every offensive Asian stereotypes: affinity for the color yellow, Fu Manchu mustache, an accent where he replaces "r" with "l" and so on. He was giant, yellow, Chinese, living egg with a prehensile mustache. He turned Steve Trevor into a living bomb and sent him to America. He exploded and killed himself and Wonder Woman. The Amazons had a machine to bring them back. After using antimatter to remove the explosive energy from the duo, the Amazons stopped Egg Fu.
As if one Asian stereotype wasn't enough, Egg Fu the Fifth appeared (we never seen Egg Fu the Second, the Third or the Fourth). Wonder Woman was captured by Egg Fu V via her own lasso. Wonder danced and used her bracelets to crack Egg Fu V.
There is a third version of Egg Fu. In the Metal Men, the giant, racial stereotype egg Dr. Yes (a reference to Dr. No) captured Will Magnus via a giant robot and brainwashed the Metal Men. He did this believing "when the Amelicans see how these gleat heroes of theirs have turned tlaitors-- they will doubt anyone's stlength to lesist us!" I notice how his accent is on and off in the same sentence.
 At a football stadium, the Metal Men destroyed themselves and their shattered parts freed Will and destroyed the robot.
Post-Crisis

He looks like a mix of Mojo from X-Men and Humpty Dumpy

After the Crisis on Infinite Earths reboot, Egg Fu returned. He was a seemly a 19th century computer on display on a carnival despite the public (rightfully) complaining about how racist it was. However, Egg Fu was actually a piece of alien technology from the Apokolips (a planet full of evil members of the New Gods). Egg Fu began to mind control people so it could teleport them to Apokolips. Hippolyta, Wonder Girl, Artemis and Donna Troy stopped Egg Fu. Metron (a not-evil / not-good New God) removed it from Earth.
A less racist version of Egg Fu appear in 52: Chang Tzu / Chung Zhu (it's spelled both ways). This version is a yellow, cracked-skinned egg  that travels via chair with mechinical spider-legs and arms. Chang Tzu kidnapped several sciencists and forced them to work in his "Science Squad". Will Magnus shot Chang Tzu. Despite this, Tzu survived somehow.
In the Outsider and Checkmate crossover "Checkout", Chang Tzu kidnapped Captain Boomerang and Sasha Bordeaux and performed torturous experiments on them until they are freed by a UN-funded superhero team. According to Thundermind, Chang Tzu is a member of the superhero team the Great Ten. Despite this, he later appeared being beaten up by Wonder Woman, Power Girl and Batgirl.
His name has been inconsistent. He was introduced as Chang Tzu. However, he also has been called "Chung Zhu". He claimed he has "nine thousand and nine unmentionable names". So, is Chung Zhu and Chang Tzu may be either two of his 9009 names or just bad writing? YOU MAKE THE CALL!
References:

• http://en.wikipedia.org/wiki/Egg_Fu
• http://www.comicvine.com/egg-fu/29-24028/