"Why do you artists always get so pissed off when someone uses your artwork? You should take it as a compliment!"

You should take it as a compliment.  
A compliment would be admiring an artist’s work where they post it, and if you want to use it that badly, complimenting them would be you have enough respect for them to ask first. Most of us don't get mad because you use it, it's because you use it without asking or pretend you didn't know who or where it came from when there's a link to where you can find the original artist on the image. Taking someone’s car to crash it in a derby isn't a compliment to them any more than taking someone’s art to wreck it or claim it is a compliment. More so without asking.

"If you didn't want it stolen, don't post it online."

Look, just because it’s there doesn’t mean it’s free to take, more so if it’s got someone’s name on it. Example: I parked my automobile on the street. Does it mean someone can hop in and take it for a spin? No, because I’m the owner of it, not you. -- “It was only sitting there; your name isn't on it!”
“Online ≠ Mine.”

A store putting a plate of cookies out on the counter doesn't make them free unless they say "free cookies!" Even then, you are better off asking in case if those cookies aren't free. Artists shouldn't have to worry about their stuff getting ganked because people can't keep their hands to themselves online. It’s called common sense. Use it! If you didn't make it or ask for it and get the “okay,” it’s not yours.

~NinjaKato

First -- When somebody is referencing a photo, they look at the pure material. When you do this, you usually look at something and enough to where it's correct and recognizable. Plagiarizing someone's art isn't the same as referencing by using photography. Copying? Yes, to a degree, but there is a hook. -- Copying a stock photo to ensure decent anatomy differs from taking someone’s illustration and copying or sketching for anatomical practice. You don't learn anything if their sense of anatomy is wrong. Photographies are someone’s property, but if they put it as stocks, or as reference material, they offer it for a free license and use by others. They took the image with their camera, but they forgo complete ownership in a way.

Second -- Copying a photograph for correct parts hardly delivers an image “not creative or original.” Creativity doesn't come from the references used; it arrives from the artistic ability to use them in a creative and inventive fashion. Copying or referencing a photograph dictates whether the result is either believable or proportioned.

Juvenile Artists don't need to worry about style. In art school, tutors aren't addressing an art style until toward the end of your junior year and through your senior year, which is when you receive guidance in “finding” your style. A style is something that develops after the basics or “reality” mastered to blend this reality convincing without breaking it. Thus forming a new reality with its own set of rules that it has learned when bent reality to the point of breaking that is what they call “crappy anatomy that makes no sense.”

Plagiarism only hinders creativity, because those who do this have never learned how to sketch the works themselves and be creative, they must have some guidelines to sketch something. It doesn't teach you to expand beyond what you are tracing; it becomes a crutch for many young Artists because of that.

Tracing teaches you nothing but how to follow a line that is in front of your pencil to recreate it, which is why it's only useful for teaching preschoolers how to write. That's why tutors encourage eyeball copying in the teen years rather than tracing because that is what still life drawing is at its source: review copying what's set up in front of you. Eyeball copying allows the artist to research the shape, part, and distance of the picture they are watching to reproduce them on paper in their style. It teaches you composition, shape, parts, negative space, anatomy, and how to “see” as an illustrator to transfer what you see through your hand on the paper.

The estimating method in an art school tutor calls “master copying,” and usually students do this in the painting class. The student chooses a picture of the expert and sketches him to his best ability. By reproducing him, he explores the methods expert used in the original creation of the work. Through the research and reconstruction of these methods, the student learns them. If you copy the work of another artist in an art school, there is a risk of throwing you out of school because of plagiarism. Even an eyeball copying from another Artist's work will expel you if it's not a reproduction exercise.

When children try to learn how to draw by copying, everything they do is hindering their development and illustration techniques, putting them behind the usual “curve” of artistic development for their age group. So, this is something, children, shouldn't learn in classes of art education in elementary school. If you want to learn how to illustrate and to praise your skills, use anatomical books for that, you can find good anatomical tutorials to improve your skills and become a better Artist than before. Better, that than risking to the Artist sues you for violating copyright. Trust me it's better.

That's why many successful illustrators are against plagiarists; the Artist allows to people plagiarize their art. But they don't allow someone shows it and claim as own because it counts as copyright infringement. Robert Granito Called a Fraud. They caught this thief for copying and taking credit for many popular comics and is now on the verge of being sued by half of the comic industry. The case is almost seven years old, but it worth a mention. Even if they got written permission to trace it, it's still not a shield that will protect them from attackers because they submitted something they didn't create. (I was a witness of that case several times.)

 
And you aren't able to create your characters? I mean, you can write out everything about them so why not write out a description as well? I cannot speak for other artists on this one, but creating a character is hard work enough, let alone drawing it out to the specs, you want. Many friends of mine that I know spend hours or even days, weeks, months, trying to come up with decent characters and they put much heart and soul into them. To you, they may be the coolest drawings, but to those who created them are part of their soul. I think several people know that if you see someone with 20 different art styles in their list of characters chances are they didn't draw them. So it's not that people are claiming they drew them (not all the time anyway). --

It's again, using our IP for your RP without asking or respecting our rights and terms as the original creator.

~NinjaKato

You cannot copyright ideas or even colors, markings, poses, and personality traits. However, images are something an artist CAN copyright. If you want to have a blue and an orange wolf character that acts like Optimus Prime, fine. You can do that, but you can't take someone's wolf version of Optimus Prime and use it as a biopic for your character without asking. Catch my drift? Write out a bio to describe your character; it works just as well if you're a good writer. -- And if you're that hard up for a visual, ask or pay the illustrator to illustrate it for you. Then your character will be made up to specs you want instead of having to steal to get something close.

~NinjaKato

Just because you found something on the Internet that doesn't mean it's free. Have you ever saw a tiny text where it says this image might fall under the copyright protection?

When you make a profile on a social network, whether Twitter, Instagram, Google+, YouTube, DeviantArt, you agree to comply with the laws of the United States. If you violate the rules multiple times, there is a risk that Companies and Artists may sue you through the United States Government, regardless of which Country you are.

Do not post the material you didn't create. In this way, you take someone's talent and steal their credit and copyright by pretending to be the Author of these illustrations. Design the work by yourself by taking a pen and paper. It will take time to become a professional illustrator, the only thing you will need much practice, patience, and effort.

If you want to use someone's work:
1. Find a way to contact an Artist via Email, Deviant Art page, IM.
2. Ask if you can use their work by addressing them to which deviation what you want to use and what plans you have to use it.
3. Ask for their written permission, to prove you could use it.
4. Provide the evidence of the original permission from an Artist, and give them credit for the work, even addressed back to the original work.

The Copyright Law of the United States tries to encourage creating art and culture by rewarding Authors and Artists with a set of exclusive rights. Copyright law grants Authors and Artists the exclusive right to make and sell copies of their works, the right to create derivative works. Including rights to perform or display their works publicly. These exclusive rights are subject to a time limit and expire 70 years after the Author's death.

The Copyright Act of 1976 governs United States copyright law. The United States Constitution exactly grants Congress the power to create copyright law under Article 1, Section 8, and Clause 8, known as the Copyright Clause. Under the Copyright Clause, Congress has the power:

To promote the Progress of Science and useful Arts, by securing for limited Times to Authors and Inventors the exclusive Right to their respective Writings and Discoveries. The United States Copyright Office handles copyright registration, recording of copyright transfers, and other Administration of copyright law.

In other words: Create art by yourself, ask for written permission before you use someone's art or material and respect copyrights.

If you want to use illustrations, you have to ask the Author who illustrated them! The Author reserves the right to write whatever terms and conditions he wishes, including to refuse your request to use his illustrations! Case closed!

[EDIT]:

I'’m sorry for this, because of several mistakes I made in the description, I had to make a set of corrections. I corrected several syntax errors and added missing words or phrases I forgot I intended to! I still have the feeling there are more errors in the description I wrote, but I don’t know what the mistakes are. I also noticed a grammatical mistake in my stamp. That is probably the ugliest stamp that I EVER revamped in my life.

Done in GIF Movie Gear.