Julius Caesar's Ghost:
Act 4, Scene 3, Lines 275 – 285

Enter the Ghost of CAESAR.   
BRUTUS: How ill this taper burns! Ha! who comes here?
I think it is the weakness of mine eyes   
That shapes this monstrous apparition.   
It comes upon me. Art thou any thing?   
Art thou some god, some angel, or some devil,  
That makest my blood cold and my hair to stare?   
Speak to me what thou art.  
GHOST: Thy evil spirit, Brutus.  
BRUTUS: Why comest thou?  
GHOST: To tell thee thou shalt see me at Philippi. 
BRUTUS: Well; then I shall see thee again?  
GHOST: Ay, at Philippi. 
BRUTUS: Why, I will see thee at Philippi, then.   
Exit Ghost.
(To read the full scene, please go to:   http://www.shakespeare-online.com/plays/julius_4_3.html)

Characteristics of Caesar's Ghost:

In drawing from his surroundings, Shakespeare includes elements of folklore, psychology, and symbolism to Caesar's ghost.  The categories are as follows:

Brutus has calmed himself after a turbulent time and he is fully awake when the ghost manifests. The dying flame of his lamp announces the ghost's presence.   Ghosts of the Middle Ages manifested with elements of their progressive decomposition; the flickering flame may well allude to the cremation of Caesar's body thus creating a personal portend for the ghost (Purkiss 152).  Caesar has returned to fulfill a vendetta as he confronts his murderer.  His primary mode of revenge is in leaving the prophecy that Brutus will fall at Philippi. This draws from Plutarch's account and ties to ancient Romans’ folklore that ghosts were allowed to speak the future (Stoll 218).  

Caesar’s ghost identifies himself as “thy [Brutus] evil spirit” (4.3.280).  Shakespeare confuses the issue through the use of the dialogue: Ghost and man echo each other with the phrase "at Philippi." Only Brutus witnesses the shade and he does so after learning of the death of his wife, Portia, and after an intensive dialogue with Cassius. Brutus, in the moment of ultimate despair, cites the ghost as one of the reasons for his suicide:  “Caesar now be still/I killed not thee with half so good a will” (5.5.50-1).

Symbolic/Political Analogy:
Elizabeth was aged and childless during the time of Shakespeare's play. Questions of succession mounted as she grew closer to death. Shakespeare, like many British subjects of the time, recalled the political turbulence that happened before she gained the throne (Rosen xiii). This creates plausibility to parallels drawn between Elizabeth and Caesar through this play. As with  Elizabeth I, Julius Caesar pulled his country from a period of unrest to one of social stability and growth. He was an elder statesman when he was killed. He had no clear male heir. For Shakespeare and England, this proved to be an issue as there existed an intense belief in the divine quality of kingship as the “only possible safeguard against civil dissension” (xiii).

Additionally, Caesar represents the actual power of political leadership.  The murder unleashes this power from its confines and is improperly usurped by the conspirators.  Julius named his heir, and thus his power, in his will:  Octavius. Similarly to Hamlet, this allows Octavius the rights of a son and thus he may avenge his adopted father's death (5.1.30-35). Power must go to the legitimate successor (Octavius). All others who have attempted to seize the power inappropriately must suffer (xix). Thus, the death of the conspirators and the victory of Octavius [Augustus] is a satisfactory conclusion for the Elizabethan audience since “established order is preferable to chaotic and violent change” (xxi).

Julius Caesar
The Tragedy of Julius Caesar: 
Life and Death of Julius Caesar (via MIT.edu):  http://shakespeare.mit.edu/julius_caesar/full.html
Literaturepage.com:  http://www.literaturepage.com/read/shakespeare_juliuscaesar.html
Classic Audio Books:  Audio recording (no visual; full cast.  2 hours 17 minutes; include stage directions in reading): 
Full length video productions:  Filmed in London (2012), this places the play in Africa.  2 hours 31 minutes.

An odd spectral fast fact:  Shakespeare inserted the word "spirit" into Julius Caesar 24 times.  The word "ghost" appears four times throughout the play.