Raw Data:
Data is pulled from the Super-wiki Table of Death, with modifications. Where the Super-wiki attributes a death to “Sam and Dean”, I’ve attributed it to the proximate causal agent- the person who struck the fatal blow/lit the match and dropped it in the grave/etc, except in the very few cases where that couldn’t be determined. I didn’t count exorcisms as “death”, since exorcised demons are just going back where they came from. Unclear dispositions, such as Famine, War and Pestilence, I’ve ignored.
Cas has two sets of data, the set of “C” columns to the right in each season counts angel kills twice, once for the angel and once for the vessel. The left set of “C” columns counts them once, ignoring the death of the vessel.
SPN (imo) de facto treats angel deaths almost all the time as if only the angel exists, ignoring the host, except in episodes that are specifically about angel/vessel interaction. But since angels appear, per 4x20 and 12x10, to always keep their vessels alive, an angel kill is, as far as we know, also always a hostage kill as well. So ideally, angel kills should be counted twice.
Unfortunately though, there’s no way to do this for demon deaths, since demons often (but not always) kill their hosts before TFW get to them. Since Cas kills a hugely disproportionate number of angels compared to Sam and Dean, counting angel kills twice and demon kills once results in Cas effectively getting his kills double-wieghted compared to the rest of TFW in some seasons. In the end, I just included both sets of data.
Discussion (1 of 3): Kills by Character and Season

(long post is long and continued under the cut)
This is SUPER interesting, and let me just high light how many more of the kills are male for people who like to accuse the show of killing women. I know other women die not at the hands of the boys but it’s worth noting.
And did Sam really not kill anything in season 1???? Wow…
GIMME 👏 THAT 👏 DATA