I can’t believe how most every one in this thread is just ignoring plants like they are not alive. If it has chlorophyll it not worth talking about.
Counting germs, trillions of little shits dead by my hands. Me and the hydrogen peroxide go way back.
Big enough to see things? God only knows how many bugs I’ve squished with my car. I swat flies and mozzies, but I have only killed a handful of spiders. I can’t get close enough to kill them.
I suppose I can count myself as the killer for all of the dozens/hundreds that I’ve made other people kill.
I’ve hit at least three birds with my car that I know of, probably more. At least one bunny with the car, and I hit a cat who lived long enough to make it to the emergency vet and I don’t know if they put it down or it just died. I blame myself for that death also. I cried for three days straight - I saw it coming and just couldn’t get out of the way. Stupid cat.
Funny tho - the worst I have ever felt over an animal death - I didn’t do it. When I was a kid, we would watch for turtles in the road or along the verges and “escort” them across the street to keep them from getting hit. We found one on some day on the way to church, and mom stopped about a quarter mile up the road - was too lazy to back up. So I ran back for it to take it across the street, reached down to pick it up - and it disentegrated in my cupped hands, spilling blood everywhere and just cracking into a dozen pieces. It was a fresh kill, and had probably just been hit. I hope to God it was dead. I just knelt there with turtle bits all over my Sunday dress, in shock.
I still dream about that damn turtle.
I killed a rabbit with my own hands when I was three years old. It turns out that bunnies aren’t a good pet for young children, because they want to hug them constantly until they stop breathing. 
Dude, anyone who lives in an industrilized country has indirectly killed people before. Buy your fiancee a diamond? Eat refined sugar? Smoke? Live someplace where the fuel going into your local power plant is unethically acquired? Wear clothes not made of leaves? It’s practically unavoidable, because by the time you’re old enough to realize it, you’ve already begun.
Anyway, by hand I’m pretty sure I’ve killed at least a fish or mouse before. There were definitely a more non-insect things when I lived in a house that I would have killed if I could friggin’ catch them. Now in the apartment, not so much.
Whenever I kill anything besides a plant- even if it’s an insect- I go out of my way to make sure it’s dead fast. I feel like an asshole if I accidentally injure a large bug instead of killing it on the first try.
I don’t kill much, including most bugs. I make an exception for flies (sometimes), roaches, and yellowjackets, because yellowjackets would so obviously kill me if they got half a chance.
I lived in rural areas, so have hit a few things…always a bummer.
My ex used to get irritated because I’d catch spiders or wasps and turn them loose; in return it nauseated me to see him kill them. My mom will walk out of her way to squash a random harmless bug on a sidewalk, and that just seems bizarre to me.
Besides bacteria and plants, I’ve killed a number of critters for food. I grew up country in a family of hunters, who I joined a couple of times. I also enjoy fishing on occasion.
I also hit a dog one late night on a country road coming home from the roller rink shortly after getting my driver’s license. I stopped to first see if he was dead or merely injured and finding him dead, went up to the door of the farmhouse there and explained what happened. I was crushed! The lady who answered the door assured me that the dog was notorious for chasing cars and that they knew that it was only a matter of time before he caught one. This was back when a lot of folks in the country and in small towns let their dogs run loose. I still was crushed.
I don’t think I could ever kill a vertebrate, I’m too big a softy. Insects and spiders are it, and only because they’re so small they can fit into bodily orifices. And even then, I only kill spiders when they land on me. I’m cool with the ones who chill up in the corners and vampirize mosquitoes like a boss. The biggest, most intelligent creature I’ve ever killed was a ***massive ***spider a couple years back. It was the biggest spider I’ve ever seen in person, although on the spider scale it’s pretty small (it’s probably smaller than every single Australian spider, for instance). Anyway, it kinda resembled a wolf spider (it was the same shape and coloring, but smaller). I found him just chilling out on my t-shirt when I went to the bathroom after going outside for a smoke. I screeched and batted him into the sink, then squished him flat with a tennis shoe. Ick! I still felt guilty afterward, though, because he was just like, “Cool bathroom, homeslice. Where we going next?” But any arachnid who lands on me is fair game… sorry, spider dude.
This story is sort of related: one time, my mom was trying to fix a flat tire in the driveway while me and my sister were watching. She lifted up the spare tire from the trunk, screamed, and dropped it right back. She had seen a mom mouse and 2 baby meece (heh) underneath it, which all got squished when she dropped the tire (whoops). I didn’t kill the micefolk, but I had to carry them on a slotted spoon to the side of the garage (my mom made me do it). I dunno if she was just too squeamish to do it herself, or thought it would help me build character, or what. Anyway, I cried and cried and gave the mouse family a proper burial.
I’m just not the killing sort. I could never kill a person (unless maybe in self-defense, but even then… I’ve never even punched a human, so it woudl take some pretty extreme circumstances to bring that out in me). I couldn’t put down mousetraps, even. Ants are gross and deserve to die, but mice are too adorable and fuzzy to kill. And people are right out.
Fish when I was much younger, no qualms about whatever bugs enter my home, and, unfortunately, more cats and dogs than I can count since I became a vet tech, including two of my own cats. That part of the job sucks ass, but I’d rather be a part of euthanasia than the suffering that happens without it. Also, injured wild things, a couple rabbits, a couple squirrels, pigeons.
Lennie?
I once shot an elephant in my pajamas…
I used to live out in the country on a cattle-ranch. I did a lot of squirrel hunting and rabbit hunting. I’ve also done the “Old Yeller” thing of mercy-killing an old and dying dog.
I went quail hunting once. Didn’t see the point of it. Using a shotgun makes it too easy. (Much prefer skeet shooting. Now that’s a fine use for a shotgun!)
In the last year I had to euthanize a horse that I cared about.
I used to say I had no regrets.
Horning in on my territory, huh? 
“Hey, buddy, what’s the big idea?! I WAS WALKING ON THAT LEG! Why don’t you just put me out of my misery?”
Yes, I’ve had to drown a few mice that got caught in traps but weren’t killed. Also a gopher. Not fun.
I killed a raccoon with my car, and it was horrible. I saw its scared eyes but it was too late to swerve or brake. If I think about it I can still see it.
Bugs, on the other hand, I kill with impunity in my home. They do not belong in my home. Die, bugs, die.
I’ll stick to vertebrates i have dispatched.
I have lost count of all the kitty cats I have flattened with my cars. Several opossums, a couple raccoons, a squirrel or two, one chicken, and a large dog also lost their lives under my wheels. In every case (except the chicken and squirrels), they ran right out in front of me at night, leaving no chance of braking or swerving.
I have killed many mice and a few rats with traps. I remember at least two mice I stomped. I have caught, killed, and eaten many fishies.
That’s so sad. 
For a long time, I felt guilty about a hamster that I had when I was young, because it died suddenly. I had forgotten to feed it for a few days before it died and I felt terrible about the possibility it may have starved to death (though looking back, I’m not sure if that was the actual reason, and it makes me feel better to think that it may not have been the reason). I definitely agree with you that young kids should not have small, fragile animals for pets. It’s too easy for unintentional harm to occur.
Anyway, I would say that I try to avoid killing whenever I can avoid it. I’m the type who puts insects outside when possible because I don’t want to kill them. I am a vegetarian (though also aware that vegetarian diets can cause deaths to small field animals and such), I advocate for shelter animals who are in danger of euthanasia, I am pro-life, I purposely didn’t get a diamond engagement ring because (among other reasons) I disagree with the violence the diamond trade causes…but still, I know I’ve contributed to plenty of deaths in my life.
In addition to the above mentioned hamster:
When I was young I had fish aquariums before I knew about the nitrogen cycle and that you DO NOT want to take an aquarium down to clean it because it will disrupt the bacteria that help keep the water healthy. Therefore a lot of my fish died prematurely due to poor water quality until I was an adult and figured out how to properly care for an aquarium. Since then, I have had to use clove oil to euthanize fish that were sick and clearly beyond help. Clove oil is the most humane way to euthanize fish IMO.
Then there was the day I was driving home from work after having a pretty good day. A bird once darted in front of my car, was hit, and I then drove over it again to be sure it would not suffer. I’m glad that I have not yet had any other roadkill incidents, because I know I would feel bad if it happened again.
Also…today I was rinsing off a houseplant that I think has spider mites. I’ve definitely killed a lot of houseplant pests.
Larger than bugs I’ve had to shoot quite a few injured or sick animals. I have no problem with those that hunt, it’s just not for me.
Well, there was that fella in Reno…