Xerek is a villain in The Incredibles. He is a criminal mastermind who was supposed to be the main villain in the first movie, but he later became a villain in the comic book series after he was replaced by Syndrome in the movie, due to the producers favoring Syndrome.
In The Incredibles and The Incredibles Comics
Xerek was originally supposed to be the main antagonist in the movie (with Syndrome being a minor villain, like Bomb Voyage and the Underminer). While not much is actually known about him, some online posts have suggested he was supposed to be Elastigirl's ex-boyfriend, who went mad when she dumped him for Mr. Incredible. His role was supposedly the same as Syndrome: lure retired Supers to Nomanisan to have them killed by the Omnidroid. However, unlike Syndrome, he would have been a "behind the desk" type villain, letting his henchmen and robots do all the dirty work.
Personality and Appearance
In a bonus feature on the DVD, a claymodel of Xerek was seen, and he was shown as a strapping gentleman in his late 30's. He was also rather tall, and wore a suit.
In the comic series, he is shown as an elderly man, obviously in his 70's-80's, thus meaning he was never Helen's boyfriend, but simply a foe she had faced many times before. In the series, he had secretly been gathering a bunch of the Incredible's enemies to become the Unforgivables. Their ultimate pan, use the villain Mezmerella's hypnosis to turn Metroville against the Incredibles, unfortunately succeeded, resulting in the family having to leave town.
Sadly, due to budget cuts, the comic series ended before the finale could be made, resulting in...
1) the villains winning (for the moment, at least)
2) the Parr's/Incredible's secrets from each other driving them apart. Xerek was indirectly responsible for this:
-Because of him, Helen had to leave town for a few days, but she knew he was to dangerous for her family to face, so she told Bob and the kids that she was going to see her parents.
-Bob decided to use this time to secretly train Dash, so he had Violet get a fake job helping out at Doc Sunbright's office (that was obviously fake, as Doc could easily have built a robot to do all these little things) so that she wouldn't tell Helen. However, the two of them got into a little argument, which ended with Bob threatening to punish Violet if she didn't do the "job" (and him not realizing how much he had hurt her feelings).
-Because of this, Violet was hurt and got her revenge by stealing technical equipment for the lab, taunting her father that the thief (her) was right in front of him the whole time. She also uses a teleporter to contact her boyfriend, Xander, who Bob doesn't really like (due to the fact that he is the son of a reformed villain), and Supers around town with him instead of doing her "job".
Before the Unforgivables attack, things are tense with the family, and during the fight, the secrets are revealed by Xerek, driving the family apart as well as out of town.
However, with The Incredibles 2 on the way, there is still hope for the comic series to possibly restart and finish properly.