This is a list of transition words used in Korean. Note that most of them are derived from 그렇다 and a connective grammar.

그러나, 그렇지만 and 하지만 - but

그래도 may translated best as "Even so" or "In spite of that".

그러면 (short: 그럼) - If so

그렇다면 - If that is the case (sounds more hypothetical than 그러면)

그래서 - So; as such (그래 가지고 has pretty much the same meaning, and is very common in colloquial speech)

그래서 그런지 - Maybe that's why

그러니까 - So; because of that

그러면서 - In the process

그렇지 않아도/안 그래도 - As it happens; even if you hadn't mentioned that

그렇지 않으면 - Otherwise, Or else

그랬더니 - So then (past/personal experience)

그러자 - Thereupon

그러므로 - Thus (sounds formal)

그럼에도 (불구하고) - In spite of that (sounds formal)

그런데도 - In spite of that (more causual)

그런데 - by the way

그러다(가) - It continued that way until...

그건 그렇고 - Anyway/Enough about that...

그나마 - And for all that...

그렇다고 (+ negative clause) - Just because that's true (it doesn't mean that X is also true).

사실은 - in fact