Horatio, friend to Hamlet

[This is an annotated list of all appearances and all mentions of Horatio.]
Hamlet and Horatio in the Graveyard by Eugène Delacroix

Christopher Plummer as Hamlet and Michael Caine as Horatio

David Tennant as Hamlet and Peter De Jersey as Horatio
"A piece of him" (1.1.19). Horatio, a bit reluctantly, comes with Marcellus to hear about the Ghost. [Scene Summary]
"Hail to your lordship!" (1.2.160). Accompanied by Barnardo and Marcellus, he comes to tell Hamlet of the Ghost. [Scene Summary]
"It is a nipping and an eager air" (1.4.2). He accompanies Hamlet to the walls of the castle to wait for the Ghost to appear again. When the Ghost does appear and gestures for Hamlet to follow him, Horatio tries to keep Hamlet from going. [Scene Summary]
"My lord, my lord" (1.5.113). Horatio and Marcellus catch up with Hamlet after the Ghost has spoken to him. [Scene Summary]
"Horatio, thou art e'en as just a man / As e'er my conversation coped withal" (3.2.54-55). Thus begins a passage of about thirty lines in which Hamlet expresses his admiration and friendship for Horatio. In the same scene, after the performance of The Murder of Gonzago, Horatio confirms to Hamlet that Claudius looked very guilty. [Scene Summary]
"Twere good she were spoken with; for she may strew / Dangerous conjectures in ill-breeding minds" (4.5.14-15), says Horatio to the Queen, of mad Ophelia. These are Horatio's only lines in the scene, and we may wonder why he's there at all. The "Gentleman" who is with him delivers the same message as he does. Also, Horatio apparently never tells Hamlet of Ophelia's madness. [Scene Summary]
"What are they that would speak with me?" (4.6.1), Horatio asks a gentleman who tells him "sea-faring" men have letters for him. This is the opening of the very short scene in which Horatio learns that Hamlet has returned to Denmark on a pirate ship. [Scene Summary]
"Custom hath made it in him a property of easiness" (5.1.67), says Horatio, when Hamlet wonders at the fact that the gravedigger sings as he digs. Horatio acts as the sounding board for some of Hamlet's flights of fancy about death. In the last part of the scene, when Hamlet jumps into the grave to struggle with Laertes, Horatio says, Good my lord, be quiet" (5.1.265), but that's all. [Scene Summary]
"So much for this, sir: now shall you see the other; / You do remember all the circumstance?" (5.2.1-2). These words of Hamlet's open the last scene of the play. Apparently Hamlet has already told Horatio some of the story of his adventures on the sea between Denmark and England; now Horatio hears the rest of the story. Horatio stays with Hamlet throughout the scene, joining him in making fun of Osric, offering to get him excused from the fencing match, and trying to join him in death. In the end, it is Horatio who explains what has happened to Fortinbras and the English Ambassadors. [Scene Summary]