Movie/show involving someone in jail

I know that this is very vague but I was trying to remember a show or a movie involving the main character going to jail and gets help from someone that’s also in jail for killing someone out of self defense or protecting someone. Not sure if the main character was good or bad. Any help would be appreciated !

Bit of a long shot with not much info, but could it be "Felon (2008)" ?

Maybe American History X

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Did you know that BATMAN has a code word to ask SUPERMAN for help because he has trouble saying he needs help.
The word is Banana Muffin.

Reindeer games?
https://www.imdb.com/title/tt0184858/

Is it a foreign movie?
The Prisoner (1990)

What you have described is pretty well the basic plot or at least subplot of most prison stories, be they movie, book, or television. But taking a shot...
An Innocent Man, perhaps?

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"Film is a disease. When it infects your bloodstream it takes over as the number one hormone. It bosses the enzymes, directs the pineal gland, plays Iago to your psyche. As with heroin, the antidote to Film is more Film." - Frank Capra

Could be Animal Factory

http://www.imdb.com/title/tt0204137/

I found it, it was gray man when Ryan gosling was explaining why he went to jail. Sorry my details were a little off, I was high when I was trying to remember the movie haha