I would say one that I know of is
King Hrothgar's despair over the inability to defeat Grendel.
Internal conflict in literature is the struggle occurring within a character's mind.
King Hrothgar is the character with internal conflict in Beowulf. He vies fro the death of Grendel but his strategies for killing Grendel have all failed meaning his goal won't/or can't be reached. Making him internally conflicted.