Players who refuse to listen to advice that may save their character from dying. A player just wanted to do things his way at the table. I mean everything. With the end result being that bad things happened to the character. Heavy armor wearing Cleric wanted to do acrobatics or climbing checks yet also wanted to always succeed at them. He almost never did. It became a joke at the table
DM: Their a pit in the ground with loss dirt around the edge of the it. What do you do?
Player X: I go take a look.
Myself or some other player: be careful the DM said their loose dirt you character may fall in plus your on the heavy side.
Player X: (Had a way of nodding to everyone who told him advice but it was his way of telling us he was ignoring us.) I'm going to take a look.
DM: Well between your rushing to the edge of the pit and the extra weight of your armor you start slide in make a Acrobatic checks to avoid falling in.
Player X (Wearing full Plate and having no ranks in Acrobatic falls down into the pit taking damage)
The same player had a bad tendency to throw fits as well at the table when that kind of thing happened trying to blame the group. When his character died because he had lost 3/4 of his hit points refused to listen to the healer of the group when asked if he needed to be healed. Began another hissy fit and I cut him off. I told him enough was enough and to stop the acting like a child at the table. He rushed ahead ignoring any attempts to stop him. He very and I mean very grudgingly admitted I had a point and calmed down. He improved somewhat at the table. It also helped that the DM was not on his side when his character died.
Players who have animal companions yet refuse to buff them or at the very least buy armor for them. Then sending them into combat and somehow expecting them not to be knocked out or killed off by npcs. Sure that may work at the first few levels. Not later on.
Players who build characters a certain way. Even if it ends up making the character performance suffer at the table. Yet it's everyone else fault for doing a better job with their character. Low Str Fighter expecting to lift, carry, hit and do as much damage as the player who built one with a higher Str. The player who expects opponents to have a hard time resisting his spells yet takes a low Int or Cha. That's fine build the character how one wants. Just don't blame everyone else for one poor choices during character creation.