They are the Great Crowd.
Revelation 7 starts with the sealing of the anointed and the symbolic tribes. Then verse 9 starts with ”After this” meaning after the anointed are sealed.
Revelation 7:9-17: “
After this I saw, and look! a great crowd, which no man was able to number, out of all nations and tribes and peoples and tongues, standing before the throne and before the Lamb, dressed in white robes; and there were palm branches in their hands. And they keep shouting with a loud voice, saying: “Salvation we owe to our God, who is seated on the throne, and to the Lamb.” All the angels were standing around the throne and the elders and the four living creatures, and they fell facedown before the throne and worshipped God, saying: “Amen! Let the praise and the glory and the wisdom and the thanksgiving and the honor and the power and the strength be to our God forever and ever. Amen.” In response one of the elders said to me: “These who are dressed in the white robes, who are they and where did they come from?” So right away I said to him: “My lord, you are the one who knows.” And he said to me: “These are the ones who come out of the great tribulation, and they have washed their robes and made them white in the blood of the Lamb. That is why they are before the throne of God, and they are rendering him sacred service day and night in his temple; and the One seated on the throne will spread his tent over them. They will hunger no more nor thirst anymore, neither will the sun beat down on them nor any scorching heat, because the Lamb, who is in the midst
* of the throne, will shepherd them
t and will guide them to springs
* of waters of life. And God will wipe out every tear from their eyes.”
So, I could be wrong but the way I am understanding this is more than just the Great Crowd come out of the Great Tribulation but the Great Crowd are the ones who after coming out of the Great Tribulation choose Kingdom Rulership. There are wicked who will also come out of the Great Tribulation but they won’t be submitting to Kingdom rulership.