Ghosts of almost all sorts appear in Shakespeare`s plays including IH6, 2H6, 118, R3, JC, Hamlet, Macbeth, and Cymbeline. Some return to visit their family and friends, some to appear to their murderers in dream or fancy, threatening revenge. In one case, the ghost explicitly commands his son to avenge his death upon the murderer. Some are subjective ghosts who either appear only to one person or is seen to one among many present, and some objective ones who so appear as to be seen by all the people present. All these aspects of Shakespeare`s ghosts will be discussed when Macbeth, Cymbeline, R3, JC, and Hamlet, the five Shakespearian plays whose ghosts return to appear to their murderers, friends and family, are to be dealt with. Both Senecan and pre-Shakespearian ghosts will be compared with Shakespeare`s to show (1) how much and well Shakespeare improved on the conventional dramatic ghosts and (2) how organically he related them to the plays involved. Banquo`s ghost twice appears to Macbeth while he is hosting a banquet. His ``gory locks`` and ``twenty mortal murthers` on his head are enough to scare Macbeth, his murderer, and to make him utter strange and self-revealing words to his guests. Banquo`s is a subjective ghost, seen only by Macbeth, but is so dramatized that his objective validity, i.e. his reality, cannot be doubted. Moreover, his appearance contributes to the course of the dramatic action by making the hero visit the weird sisters to know what is in store for him and to act accordingly. The ghosts of Posthumus` parents and brothers whom he sees in his dream are also subjective ghosts, seen only by Posthumus and no one else. But what they speak about their son and brother and appeal to Jupiter and what Jupiter who has, in response to their appeal, just descended in thunder and lightning and on an eagle, tells them about their beloved Posthumus together with his ``tablet`` are enough to give the ghosts their reality. In R3 the ghosts of Prince Edward, Henry VI, Clarence, Rivers, Grey, Vaughan, Hastings, two young princes, Lady Anne and Buckingham appear, on the eve of the decisive baffle of Bosworth, to Richard, their murderer, and then to Richmond, Richard`s rival. They urge the former to despair and die with all sorts of curses while they encourage the latter to live and flourish, saying that "the wronged souls/Of butchered princes fight in thy behalf ". These ghosts are doubtless subjective ones, but that they appear not only to Richard but also to Richmond would not allow them to remain just subjective because it helps to contribute somewhat to the establishment of their objective validity. Moreover, their appearance brings about a very tangible result by producing from Richard and Richmond such respective responses as "Methought the souls of all that I had murtherd/Came to my tent, and every one did threat/To-morrow`s vengeance on the head of Richard" and "Methought their souls whose bodies Richard murther`d/Came to my tent and cried on victory". And the battle ends with Richard`s defeat and Richmond`s victory as the ghosts wished and foretold them. In short, the ghosts influence the action and prove their reality. Similar to these ghosts is the ghost of Caesar. The ghost appears to Brutus, his murderer, on the eve of the decisive baffle of Philippi while he sleeps in his tent. the fact that the ghost has already appeared to him at Sardis once and that he validity or reality. Needless to say, the ghost`s appearance influences Brutus, who says, "Now I have taken heart you vanishest", and, of course, he takes his own life, saying, "Caesar, thou art reveng`d,/Even with the sword that kill`d thee" and "0 Julius Caesar, thou art mighty yet!". With his mortal presence in the first part of the play and with his ghostly presence in the second part of the play Julius Caesar proves himself the unifying principle of the tragedy, indeed the hero in every sense of the word. Pre-Shakespearian ghosts derived, at least partly, from classical, especially from Senecan ghosts. Senecan ghosts are the combination of Euripidean type of prologue-ghost and Aeschylean type of revenge-ghost. Being prologue-ghosts, the ghost of Tantalus in 7hyesres and that of Thyestes in Agamemnon do not participate in the action itself, but repeat the word revenge from time to time. Another characteristic of Senecan ghosts is their description or mention of the pains and tortures that take place in Tartarus such as Sisyphus endless rolling of a large stone to the top of a hill, Ixions being bound on a wheel that turns for ever, Tantalus` eternal thirst or hunger, and Tityus` (Titius`) vultures tearing at his liver, all of which Senecan ghosts describe in rant or bombastic style. These Senecan ghosts and the English translations of all of Senecan tragedies, starting Jasper Heywood`s troas in 1559, together influenced pre-Shakespearian ghosts. Heywood refused to remain a meer translator but introduced a ghost, providing him with a lengthy prologue-speech at the beginning of the 2nd act of troas with vengeance as the theme of its refrain. This original and creative attitude towards the dramatic ghosts grew` as Seneca-modelled English plays either in the form of Anglo-Latin tragedies or in the form of early classical English tragedies became more and more popular. Never-ending punishments cited above are though the ghost himself do not appear in them. The ghost of Gorlois in The prototypes by reappearing at the end of the play. This, together with Heywood`s ghost of Achilles, marked a development of Senecan ghosts. And further devel-opment was made in both anonymous Locrine and Thomas Ky d`s The Spanish Tragedies. The ghost of Albanact in Locrine influences the plot or action of the play, thus improving on Senecan ghosts, whereas The Spanish Tragedy dem onstrated its unique utilization of Senecan ghost-machinery. The play opens with the dialogue between the Ghost of Andrea and Revenge, the exact counterparts of the Ghost of Tantalus and Fury (Megaera) in 7hyestes. Here the ghost is not only just Senecan prologue-ghost serving as a chorus but also an epilogue-ghost. But Kyd made his ghost`s speeches even more bombastic than those of Senecan ghosts and did not make any effort to substitute English ghost-lore for Senecan ghost machinery. Marston`s ghosts in Antonio`s Revenge mark, however, yet another step forward taken for the development of the English dramatic ghosts because although there are frequent visitations of ghosts shouting ``vindicta!! revenge!``, we find none of Senecan ghost-machinery used in it. But the greatest development was to be made by Shakespeare in his ghost of King Hamlet, for Shakespeare refused to use Senecan ghost machinery and got rid of the rant of Senecan ghosts altogether, thus successfully substituting English ghost-lore instead. Moreover, he humanized the ghost by demonstrating how absolutely he still loved and cared for his wife. Above all, the ghost of King Hamlet is an objective ghost as well as a very organic one on whom the entire dramatic action depends. In conclusion, ghosts in Shakespeare not only testify Shakespeare`s dramatic genius but comprise almost all English ghost-beliefs or ghost-lore material known to his day.