Even if the character I create in script/short movie/selfpublished comic/online blog is so distinguished that it's obviously a theft if somebody else is useing it in their work?
In that case you need a trademark not the copyright. What is
"obviously theft" and what is legally theft are quite different.
Let's use GuerrillaAngel's Super Yoga Woman as an example;
You can trademark the costume and hairstyle and the name
as it is connected to the script/short movie/selfpublished comic/
online blog. But you cannot hold the copyright on the three
words. Anyone can still create a woman who is "super" in yoga.
If I make a new sequel for Indiana Jones bymyself in my own production the way I like it, do I need to pay to speilberg/lucas for usage of Harrison Ford's character?
Josh is correct. If speilberg/lucas were to agree to license the Jones
character to you you would have to pay them. You would not be
violating copyright or trademark if you had a lawyer in a suit
working in Chicago who's name was Indiana Jones. It is the total
combination that would get you into trouble. Even if you changed
very little (say you took away the whip and the Fedora) you could
still face legal issues.
Josh posted a great link; "allows the use of a mark in such a way
as to not lead to such confusion in the minds of the public." If your
use leads people to believe they are watching the LucasFilm character
then you are in violation. If no reasonable person can be confused
by your character you are likely to be in the clear.