We can't go and point out all the worst mothers in comic book history without throwing all the deadbeat, terrible dads under the bus, now can we? There have been some pretty bad dads in real life, and those guys were limited by all sorts of crazy laws, both the legal ones and those pesky laws of physics. You open up a comic book, and 'deadbeat dad' takes on a whole new meaning!
The list of this guy's faults is just too big. He seduced his son's lady, impregnated her with twins, emotionally abused his son, and was just an all around a-hole of a father. You name it, he most likely did it to Harry.
An abusive assbutt, Brian was abused by his own father, and passed that abuse on to his own kid, Bruce. To make sure the kid was screwed up, Brian killed his son's mother in front of him, and went away for 15 years. Is it a surprise that, when his dear old dad got out of the asylum, Bruce ended up killing him by smashing his head into his mom's headstone?
See the bit about Talia Al Ghul for the mother side of this (link). Batman, not one to make the best decisions in life, has a one night stand with his sworn enemy's daughter, and never knew she had a kid. Damian eventually joined his father in his crimefighting, and Bruce took over for the bad parenting from Talia. Damian was constantly in danger of being harmed or murdered, and was eventually killed by a man sent by his own mother to kill him.
Given, the only choice Jor-El had was to either have his entire family die when Krypton went boom, or pull an intergalactic door-drop with his baby, so there really wasn't a very good chance there to be a stand-up parent. Oh hey, except for this; BUILD A SPACESHIP THAT FITS TWO, MAYBE EVEN THREE PEOPLE. Then you can send your son off with mom and/or dad, or at least a cousin or something.
Another example of not knowing he was the father of soon-to-be screwed up kids, his wife gave birth to the future twincesters Pietro and Wanda, unbeknownst to Magneto. Some time after Wanda finds out her father is Magneto, she loses her own children she had (using magic) with her android husband Vision. She tries to bring them back, fails, ends up killing a whole lot of mutants, meets two kids who believe they're her reincarnated kids, tries to kill herself, and....yeah, not great mother material, and mostly thanks to the wonderful parenting of Magneto and his wife.
Not having the best dad growing up, you really couldn't expect Logan to be a good dad, if the opportunity ever arose. Apparently, he wasn't, either; he had bastard children all over the damn globe. Well, as it always happens, a bad man rounded them all up and trained them to fight Wolverine one day. Of course Wolverine won, but little did he know he had just slaughtered all his kids.
Like I said, a slightly weird situation, so he gets the bonus spot on this list!
Any other not-so-superdads I missed? I don't need to say to let me know in the comments, because I know you will!