For anyone open to the Catholic interpretation...
The Church has definitively taught from very ancient times that the 24 elders represent the 12 tribes of Israel of the Old Testament, and the 12 Apostles of the New Testament.
This doctrine is actually so close to the heart of the Church that it is incorporated into the Mass.
Many non-Catholic as well as Catholic scholars have noticed that the whole structure of Revelation is a big Passover liturgy where Christ, the Priest King, the firstborn Son and the Lamb looking as though it's been slain conducts and celebrates the heavenly liturgy. And the earthly liturgy is meant to be a reflection in that, a participation in that, and the early Church took it for granted.
In Chapter 4, verse 8 of Revelation we read:
8 Each of the four figures had six wings, with eyes everywhere looking
outwards and inwards; day and night they cried unceasingly, Holy,
holy, holy is the Lord God, the Almighty, who ever was, and is, and is
still to come. 9 And as often as these figures gave glory and honour
and blessing to him who sat on the throne, who lives for ever and
ever, 10 the twenty-four elders fell down in worship before him who
sat on the throne, who lives for ever and ever, and threw down their
crowns before the throne, crying out,3 11 Thou, our Lord God,
claimest as thy due glory and honour and power; by thee all things
were created; nothing ever was, nothing was ever created, but in
obedience to thy will.
Notice that it says:
…[A]s often as these figures gave glory and honour… the twenty-four
elders fell down in worship…
This scene is acted out practically verbatim during the Catholic Mass. Each Mass, during the Liturgy of the Eucharist the following transpires:
Priest: The Lord be with you.
All: And also with you.
Priest: Lift up your hearts.
All: We lift them up to the
Priest: Let us give thanks to the Lord, our God.
All: It is
right to give him thanks and praise.
Holy, Holy (Sanctus):
All: Holy, holy, holy Lord, God of power and might, Heaven and
earth are full of your glory. Hosanna in the highest. Blessed is he
who comes in the name of the Lord. Hosanna in the highest!
Immediately after this prayer is prayed, all who are gathered around the Eucharist on the altar kneels down in reverence, just as the 24 elders do in St. John’s vision.
This eternally symbolic adoration is again echoed in chapter 5 of St. John’s vision:
…[T]he four beasts and four and twenty elders fell down before the
Lamb, having every one of them harps, and golden vials full of odours,
which are the prayers of saints.
As stated above, Catholic theology understands the number of the elders (24) to be both the 12 tribes of Israel, as well as the 12 Apostles. The 12 tribes are symbolic of all of God’s children in the Old Testament, or before Christ. It obviously follows that the 12 Apostles represent all of God’s elect until the end of the world. This is a perfect example of how St. John uses numeric signs and symbols throughout his Apocalypse.
The footnote entry for Revelation 4:8 in the New American Version (Catholic bible) is as follows:
[4:1–11] The seer now describes a vision of the heavenly court in
worship of God enthroned. He reverently avoids naming or describing
God but pictures twenty-four elders in priestly and regal attire
(Rev 4:4) and God’s throne and its surroundings made of precious gems
and other symbols that traditionally express the majesty of God (Rev
4:5–6). Universal creation is represented by the four living creatures
(Rev 4:6–7). Along with the twenty-four elders, they praise God
unceasingly in humble adoration (Rev 4:8–11).
Twenty-four elders: these represent the twelve tribes of Israel and the twelve apostles; cf. Rev 21:12–14.
In his General Audience of Jan. 12, 2005, Blessed John Paul the Great preaches a sermon entitled By the Blood of the Lamb. He begins his edifying exposition of this perennial Catholic doctrine by commenting on how the 24 elders represent the worship of God’s chosen people:
The hymn that has just resounded ideally comes down from heaven. In fact, the Book of Revelation that presents it links the first part (cf. 11: 17-18) to the "twenty-four elders who sit on their thrones before God" (11: 16), and in the second strophe (cf. 12: 10-12) to "a loud voice in heaven" (12: 10).
We are thus involved in a grandiose portrayal of the divine court where God and the Lamb, that is, Christ, surrounded by the "Council of the Crown", judge human history in good and in evil but also reveal history's ultimate end of salvation and glory. The role of the Canticles that spangle the Book of Revelation is to illustrate the topic of the divine lordship that controls the often bewildering flow of human events.
In this regard, the first passage of our Canticle is significant. It is set on the lips of the 24 elders who seem to symbolize God's Chosen People in their two historical phases, the 12 tribes of Israel and the 12 Apostles of the Church.
Now, the almighty and eternal Lord God "has taken [his] great power and begun to reign" (11: 17). His entry into history does not only aim to curb the violent reactions of rebels (cf. Ps 2: 1, 5), but above all to exalt and reward the just. These are defined with a series of words used to describe the spiritual features of Christians. They are "servants" who comply faithfully with the divine law; they are "prophets", endowed with the revealed word that interprets and judges history; they are "saints", consecrated to God, who revere his name, that is, they are ready to adore him and to do his will. Among them there are "small and great", an expression dear to the author of the Book of Revelation (cf. 13: 16; 19: 5, 18; 20: 12) which he uses to designate the People of God in its unity and variety.