(adj) To be known is to be popular (good or bad) for one reason or another. Like the guy who fell off the top of the BMW, or the girl who accidentally had sex with a watermelon.
"You've been known ever since you said ZOMG in your sleep at band camp."
Someone you know is known. When you know somebody, you don't have to test them to know who they always were.
1) The guy was a relative of him/her, so he didn't need to test him/her to know who he/she really was, he had known him/her growing up.
2) The guy had spent years around him/her at work, so he knew who he/she really was without having to test him/her. The other worker/coworker was known to him.
A fault or defect in a system or machine that has been documented, but not yet fixed. A "known issue" differs from a "bug" in the sense that "bugs" are unknown, or at the very least undocumented.
"Customer Service, how may I help you?"
"Oh my god! I bought your new product and when I turned it on it began systematically hunting and killing my friends and family!"
"Yes, that is a known issue."
"What?!"
"It's documented."
Someone who is a well-known/relevant member within a community due to their unfathomably egotistical personality. They will oftentimes have large egos but lack any sort of self-esteem. They also display a desperate craving for validation from their peers because they are physically incapable of having their own sense of self-worth.
Ever since that known shitter won the Fortnite World Cup, he hasn't shut up about it. He needs to go get some bitches or something.