s l i m e b e a s t
Biggest times (also the ones where it was most obvious):
The company that made the "Trash Pack" figures had a Facebook page where I posted some original designs. I then spoke with someone at the company who asked to see my portfolio. There was no response after that, but within a couple months they had figures very similar to what I sent them advertised. I sent them a "Space Trash" line concept with a satellite, alien, meteor, etc. Things that in no way were like what they currently did (legitimately just trash from your garbage can) so when they released "Astro Trash" with the same exact theming for every figure it was patently obvious.
The funny part is, trash in space is literally called "Space Junk" or "Space Trash" most commonly, but because they took my set of designs, they changed the name to be safe, so it was "Astro Trash". Like, a big reach for how to name it differently. XD
Additionally, I submitted designs for a line called "O.M.F.G." by October Toys - this was an actual contest. Things similar to mine would then pop up, which is hard to tell if it's intentional of course -- BUT -- one dude liked one of my designs so much he just straight-up re-drew it and told me to use his version. I said "no, but I appreciate it", so he went behind my back and had someone else sculpt his version. He then tried to get me to give him the green light to use/sell it, which I again said "no" to, causing him to freak out.
That guy later went on to run a mini-figure group on Facebook. I joined it and posted some of my stuff. He was like "You're that guy who wouldn't let me use his design!" and dropped a ban. lol
With that same contest, I actually helped out a dude who was using MS Paint and redesigned his entry for him - saying he could use it or not as he wished and I wouldn't be hurt either way. Years later, I saw the figure I had drawn for him being released for sale and had to email him saying, like... "Hey, so uh, you know that was some help for that contest and not just to use to produce your own figure way later, right?"
People be greedy and childish, for real.
A PUMPKIN MAAAAAN
I used to submit designs to mini-figure contests and companies, but people would just steal them. XD Luckily, they'd change enough to get away with it - but that also means the designs weren't "as cool" as mine, just from my PoV. :B