Rosencrantz and Guildenstern's motto was Ingen Bekymringer which also means No worries for the rest of your days, which taught Hamlet to ignore responsibility and just ignore the whole Claudius thing.
Rosen and Guilden are also probably dead, but I haven't read the original story, and I don't plan on doing so... 29,551 WORDS?!?!
The (possibly?) gay couple that Hamlet is friends with in the play of the same name.
They are duped by Claudius into escorting Hamlet to England to be killed, but Hamlet escapes. Rosencrantz and Guildenstern then unwittingly meet the English King, and and hand him a letter instructing him to kill them both. They die. Nobody cares.
In the play, they always appear together, and seem to be entirely co-dependent. They have no real individual traits.
Despite the fact that they are fairly minor characters, they have a sort of cult status. Tom Stoppard wrote a famous play called "Rosencrantz and Guildenstern Are Dead", which tells the story of Hamlet from their perspective.