Messiah according to Islam is Hz. Isa (Jesus). But the one who Jews are waiting for is Hz. Mahdi. Hz. Mahdi and Hz. Isa (Jesus) will move together to make Islam prevail all over the world.
I want to share with you some ayahs about Hz. Isa returns:
When God said: "Jesus, I will take you back and raise you up to Me, and purify you of those who are unbelievers. And I will place the people who follow you above those who are unbelievers until the Day of Resurrection. Then you will all return to Me, and I will judge between you regarding the things about which you differed. (Surah Al 'Imran, 3:55)
Those who say that the Messiah, son of Mary, is the third of three are unbelievers. There is no god but the One God. (Surat al-Ma'ida, 5:73)
There is not one of the People of the Book who will not believe in him before he dies; and on the Day of Resurrection he [Jesus] will be a witness against them. (Surat An-Nisa', 4:159)
And [on account of] their saying: "We killed the Messiah, Jesus son of Mary, Messenger of God." They did not kill him and they did not crucify him, but it was made to seem so to them. Those who argue about him are in doubt about it. They have no real knowledge of it, just conjecture. But they certainly did not kill him. (Surat An-Nisa', 4:157)
God raised him [Jesus] up to Himself. God is Almighty, All-Wise. (Surat An-Nisa', 4:158)
There is not one of the People of the Book who will not believe in him before he dies; and on the Day of Resurrection he [Jesus] will be a witness against them. (Surat An-Nisa', 4:159)
When an example is made of the son of Mary [Jesus], your people laugh uproariously. They retort: "Who is better then, our gods or him?" They only say this to you for argument's sake. They are indeed a disputatious people. He is only a servant on whom We bestowed Our blessing and whom We made an example for the tribe of Israel. If We willed, We could appoint angels in exchange for you to succeed you on Earth. (Surat Az-Zukhruf, 43:57-60)
He [Jesus] is a Sign of the Hour. Have no doubt about it. But follow me. This is a straight path. (Surat Az-Zukhruf, 43:61)
He [Jesus] is only a servant on whom We bestowed Our blessing and whom We made an example for the tribe of Israel. (Surat Az-Zukhruf, 43:59)
When the angels said: "Mary, your Lord gives you good news of a Word from Him. His name is the Messiah, Jesus, son of Mary, of high esteem in this world and the Hereafter, and one of those brought near [to God]. He will speak to people in the cradle, and also when fully grown, and will be one of the righteous." She asked: "My Lord! How can I have a son when no man has ever touched me?" He said: "It will be so. God creates whatever He wills. When He decides on something, He just says to it: 'Be!' and it is. He will teach him the Book and Wisdom, and the Torah and the Gospel." (Surah Al 'Imran, 3:45-48)
God, there is no god but Him, the Living, the Self-Sustaining. He has sent down the Book to you with truth, confirming what was there before it. And He sent down the Torah and the Gospel previously. (Surah Al 'Imran, 3:2-4)
[Jesus said,] "Peace be upon me the day I was born, the day I die, and the day I am raised up again alive." (Surah Maryam, 19:33)
Remember when God said: "Jesus, son of Mary, remember My blessing to you and to your mother when I reinforced you with the Purest Spirit so that you could speak to people in the cradle and when you were fully grown [kahlaan]…" (Surat al-Ma'ida, 5:110)
He will speak to people in the cradle, and also when fully grown [kahlaan], and will be one of the righteous. (Surah Al 'Imran, 3:46)
Kahlaan, which is used only in these two verses, only in reference to Jesus, and to express Jesus' adulthood means "someone between the age of 30 and 50, someone who is no longer young, someone who has reached the perfect age." Islamic scholars agree that it denotes the age of 35 or above. They base their views on a hadith reported by Ibn 'Abbas that Jesus was raised up to God's presence in his early 30s, and that he will live for 40 years when he comes again. Therefore, they suggest that this verse is evidence for Jesus' return, since his old age will occur following his second coming. (Only God knows for certain.)
And you can also access all information about Hz. Mahdi from here:
http://www.awaitedmahdi.com/