I haven't had a problem with this but reading other places kind of makes me facepalm. That said, I will elaborate. Just in case...
Any vector I make that is directly traced from a screen cap, comic, or other piece of art, should be considered property of the original artist. Unless it is an original piece I made, I don't claim any ownership. I simply allow a high resolution version of others works to exist. Think of it as gifts for the original artist.
As such, I have absolutely no opinion how the vector is used. That is not to say, however, that the original artist/owner doesn't have a say. I do check to see if an artist has a problem with their work being vectored and I respect their requests. So should you. If you want to use something of mine, check with the original owner to see if it's okay with THEM.
In my opinion, if you are comfortable putting your stuff on the internet, you should be comfortable with the fact that is can/may/will get downloaded/used/reposted somewhere. The people of the internet tend to consider themselves free to do whatever they want. There's no stopping them, so I say just go with the flow. When in Rome, do as the Romans do.
I'm not endorsing art theft. That is, claiming ownership to someone else's works. I think claiming ownership to something and using/uniquely reposting something are two different things. In the future, I may change my opinion, but as it is, I don't care if things I make are used.
And yes, this was a long schpeel saying that if Hasbro or Cartoon Network HAPPEN to want to use vectors I've made from screen caps or concept art, I have no complaint. It belongs to them, after all.
Feel free to argue with me in the comments. lol