1) Polonius to his son Laertes who is departing for France (1.3.84):
"This above all: to thine own self be true,
And it must follow, as the night the day,
Thou canst not then be false to any man."

2) Hamlet's description of the less-than-natural relationship between himself and Claudius (1.2.67):
"A little more than kin and less than kind."

3) Ophelia to her brother Laertes who is giving her advice on her relationship with Hamlet (1.3.51):
"Do not, as some ungracious pastors do,
Show me the steep and thorny way to heaven,
Whiles, like a puffed and reckless libertine,
Himself the primrose path of dalliance treads
And recks not his own rede."

4) The ghost to Hamlet, describing the true cause of his death (1.5.33):
"Murder most foul, as in the best it is,
But this most foul, strange, and unnatural."

5) Hamlet to himself (3.1.64):
"To be or not to be-that is the question:
Whether 'tis nobler in the mind to suffer
The slings and arrows of outrageous fortune,
Or to take arms against a sea of troubles
And, by opposing, end them."

6) The Player King performing the words Hamlet has written for him (3.2.234):
"Our wills and fates do so contrary run
That our devices still are overthrown;
Our thoughts are ours, their ends none of our own."

7) Hamlet to Rosencrantz and Guildenstern on his madness (2.2.402):
"I am but mad north-north-west.  When the wind is southerly, I know a hawk from a handsaw."

8) Marcellus to Horatio after Hamlet follows the ghost (1.4.100):
"Something is rotten in the state of Denmark."

9) Hamlet to Laertes prior to their duel (5.2.252):
"Hamlet is of the faction that is wronged;
His madness is poor Hamlet's enemy."