Baymax - Nope! All clear here!

Murdermax - Anywhere from 0 to 1 person, possibly others, depending on the AU/RP/whatever (I generally go with him having killed one person)

Space Marine Ralph/Space Cadet - Unknown, he's killed lots of Cy-Bugs, but they're not people. If he's turned into a Cy-Bug during gameplay, then he'll have killed his fellow Marines. He may have killed

people in his backstory, depending on the missions, but he doesn't clearly remember them.

Wreck-It Ralph - At least one person over and over and over - He kills Felix either 3 or 4 times per quarter, more if they earn extra lives. He also caused at least one accident after hours that ended up

killing Felix. It's unknown if throwing Gene causes him to die, but likely he's gone overboard and has possibly killed some Nicelanders in the process of gameplay or throwing a tantrum after hours.

Not to mention he's the cause of death for the bad guy at the end, however he didn't directly do it, rather, he set off a chain reaction.

Based on the way other characters act around Ralph during the beginning of the movie, he may have killed other character in their own games, though it could have been an accident.

TL;DR - Wreck-It Ralph has a lot of blood on his hands