Hebrews 1:8 But to the Son He says Your throne O God

(Hebrews 1:8 [NIV]) But about the Son he says, "Your throne, O God, will last for ever and ever, and righteousness will be the scepter of your kingdom.

(Hebrews 1:8 [KJV]) But unto the Son he saith, Thy throne, O God, is for ever and ever: a sceptre of righteousness is the sceptre of thy kingdom.

(Hebrews 1:8 [TR]) προς δε τον υιον ο θρονος σου ο θεος εις τον αιωνα του αιωνος ραβδος ευθυτητος η ραβδος της βασιλειας σου

We find the NWT translates it as:
(Hebrews 1:8 [NWT]) But with reference to the Son: "God is your throne forever and ever, and the scepter of your kingdom is the scepter of uprightness.

Let's discuss this translation.

1. Introduction: Nominative for Vocative
Definition:  A substantive in the nominative is used in the place of the vocative case. It is used (as is the voc.) in direct address to designate the addressee. [1]


(Psalms 22:2 [LXX]) (21:3) ο θεος μου κεκραξομαι ημερας
(Psalms 22:2 [KJV]) O my God, I cry in the daytime

(Luke 8:54 [TR]) η παις εγειρου
(Luke 8:54 [KJV]) Maid, arise.

(John 17:25 [TR]) πατερ δικαιε
(John 17:25 [KJV]) O righteous Father

(John 19:3 [TR]) χαιρε ο βασιλευς των ιουδαιων
(John 19:3 [KJV]) Hail, King of the Jews!

(Revelation 6:10 [TR]) ο δεσποτης ο αγιος και ο αληθινος
(Revelation 6:10 [KJV]) O Lord, holy and true,

2. Grammatical analysis by Daniel B. Wallace [1]

There are three syntactical possibilities for θεός here: as a subject (“God is your throne”), predicate nominative (“your throne is God”), and nom. for voc. ("Your throne, O God"). The S and PN translations can be lumped togetherand set off against the nom. for voc. approach. It is our view that the nom. for voc. view is to be preferred for the following reasons:

(1) It is an overstatement to argue that if a writer wanted to address God he could have used the vocative θεέ, because no where in the NT is this done except in Matt 27:46. The articular nom. for voc. is the almost universal choice.

(2) This is especially the case in quoting from the LXX (as in Heb 1:8; Heb 10:7), for the LXX is equally reticent to use the voc. form, most likely since Hebrew lacked such a form.

(3) The accentuation in the Hebrew of Ps 45:7 suggests that there should be a pause between “throne” and “God” (indicating that tradition took “God” as direct address).

(4) This view takes seriously the μένδέ construction in vv 7–8, while the S-PN view does not adequately handle these conjunctions. Specifically, if we read v 8 as “your throne is God” the δέ loses its adversative force, for such a statement could also be made of the angels, viz., that God reigns over them.

3. Old Translations

a. Sahidic Coptic:

(pekethronos epnoute shob sha eneh ente pieneh)
ϢΟΟΠ: (from ϢШΠΕ) means 'to be' or 'to exist' and it precedes ϢΑ ΕΝΕϨ ΝΤΕ ΠΙΕΝΕϨ, which means 'to the age of the age' (forever / eternity)

So the meaning, as G. Horner translates it, would be:

(Hebrews 1:8 [CopticS, Horner])
but to the Son, Thy throne, God, is being unto age of the age; and the staff of the straightness is the staff of thy kingdom.

b. Targum of Psalm 45:7
כורסי יקרך יהוה קיים לעלמי עלמין \חוטרא תריצתא חוטרא דמלכותך׃
The throne of your glory, O Lord, lasts forever and ever; the scepter of your kingdom is an upright scepter.

As we can see,
O Lord is used, which is vocative.

c. Peshitta, with Younan's interlinear
(Hebrews 1:8 [Peshitta]) ܥܠ ܒܪܐ ܕܝܢ ܐܡܪ ܕܟܘܪܤܝܟ ܕܝܠܟ ܐܠܗܐ ܠܥܠܡ ܥܠܡܝܢ ܫܒܛܐ ܦܫܝܛܐ ܫܒܛܐ ܕܡܠܟܘܬܟ ܀
Concerning.The Son.but.He said.Your throne.yours.Oh God.to eternity.of eternities.a scepter.straight.the scepter.of Your kingdom

4. Early Quotations
That as God, He is king before the ages that prophetic minstrelsy teaches us in the words “Thy throne, O God, is for ever and ever; the sceptre of Thy kingdom is a right sceptre.” [2]

And of the angels He saith, ‘Who maketh His angels spirits, and His ministers a flame of fire’: but of the Son He saith, ‘Thy throne, O God, is for ever and ever; a sceptre of righteousness is the sceptre of Thy kingdom,’ ” and all else that the prophecy recites together with these words in declaring His Godhead. [3]

At least Paul puts it. as a peculiar privilege of the Only-Begotten, saying, “To which of the angels said He at any time, Sit thou on my right hand? And of the angels He saith, who maketh His angels spirits;” but unto the Son, “Thy throne, O God.” [4]

5. Other Occurrences of the word "Throne" in the Bible
First of all,
(Psalms 45:6 [KJV]) Thy throne, O God, is for ever and ever: the sceptre of thy kingdom is a right sceptre.

but of course the NWT changed this too.

The word "throne" was mentioned 165 times in the KJV.
Nowhere in all these occurrences was it mentioned that God is the throne of someone.

However, we see resemblance between this translation
(Hebrews 1:8 [KJV]) Thy throne, O God, is for ever and ever
(Psalms 9:7 [KJV]) But the LORD shall endure for ever: he hath prepared his throne for judgment.
(Psalms 93:2 [KJV]) Thy throne is established of old: thou art from everlasting.
(Psalms 103:19 [KJV]) The LORD hath prepared his throne in the heavens; and his kingdom ruleth over all.
(Lamentations 5:19 [KJV]) Thou, O LORD, remainest for ever; thy throne from generation to generation.
(Psalms 145:13 [KJV]) Thy kingdom is an everlasting kingdom, and thy dominion endureth throughout all generations.
(Psalms 146:10 [KJV]) The LORD shall reign for ever, even thy God, O Zion, unto all generations. Praise ye the LORD.
(Exodus 15:18 [KJV]) The LORD shall reign for ever and ever.
(Psalms 29:10 [KJV]) The LORD sitteth upon the flood; yea, the LORD sitteth King for ever.

So I think that we can conclude that this is the correct translation:
(Hebrews 1:8 [KJV]) But unto the Son he saith, Thy throne, O God, is for ever and ever: a sceptre of righteousness is the sceptre of thy kingdom.

[1] Daniel B. Wallace. (1999; 2002). Greek Grammar Beyond the Basics - Exegetical Syntax of the New Testament
[2] The Nicene and Post-Nicene Fathers Second Series Vol. III (318).
[3] The Nicene and Post-Nicene Fathers Second Series Vol. V (156–157).
[4] The Nicene and Post-Nicene Fathers Vol. X (400)