Daniel saw four beasts:

Daniel 7:3 And four great beasts came up from the sea, diverse one from another.

  4 The first was like a lion, and had eagle’s wings: I beheld till the wings thereof were plucked, and it was lifted up from the earth, and made stand upon the feet as a man, and a man’s heart was given to it.

  5 And behold another beast, a second, like to a bear, and it raised up itself on one side, and it had three ribs in the mouth of it between the teeth of it: and they said thus unto it, Arise, devour much flesh.

  6 After this I beheld, and lo another, like a leopard, which had upon the back of it four wings of a fowl; the beast had also four heads; and dominion was given to it.

  7 After this I saw in the night visions, and behold a fourth beast, dreadful and terrible, and strong exceedingly; and it had great iron teeth: it devoured and brake in pieces, and stamped the residue with the feet of it: and it was diverse from all the beasts that were before it; and it had ten horns.

Daniel wanted to know the truth of all this:

Daniel 7:16 I came near unto one of them that stood by, and asked him the truth of all this. So he told me, and made me know the interpretation of the things.

  17 These great beasts, which are four, are four kings, which shall arise out of the earth.

This is to be future to Daniel, "which shall arise out of the earth".

But it may not only be speaking of the near future, like the Persians, Greeks, and the Romans.

It looks to also be speaking of the time of the end of the tribulation, when Jesus has the antichrist cast alive into the lake of fire:

Daniel 7:11 I beheld then because of the voice of the great words which the horn spake: I beheld even till the beast was slain, and his body destroyed, and given to the burning flame.

 

And if so, it says that the first three beasts aren't destroyed, but their rule is ended, yet they apparently enter the kingdom alive:

Daniel 7:12 As concerning the rest of the beasts, they had their dominion taken away: yet their lives were prolonged for a season and time.

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