Who is the 12th apostle to replace Judas?

Who was the 12th Apostle to replace Judas, and why was Judas no longer considered an apostle?

The twelfth apostle to replace Judas was Matthias, as described in Acts 1.

Acts 1:21 “Therefore it is necessary that of the men who have accompanied us all the time that the Lord Jesus went in and out among us —
Acts 1:22 beginning with the baptism of John until the day that He was taken up from us — one of these must become a witness with us of His resurrection.”
Acts 1:23 So they put forward two men, Joseph called Barsabbas (who was also called Justus), and Matthias.

To be considered an apostle, Peter says candidates must have been with Jesus from the time of the baptism of John until the resurrection. They must have received John's baptism and seen the resurrection of Christ. Only two men among those who followed Jesus met those qualifications, and after throwing lots, Matthias was chosen.

Matthias is mentioned in scripture only in that chapter, but his low profile is not unusual. The lives of most of the twelve apostles are given little or no attention in scripture. Only a handful (e.g., Peter, John, James) are given an extended mention because of their leadership roles in the first century. Nevertheless, the Bible is clear on who were the first twelve apostles of the church, and though Judas was called as an apostle for a time, he was never intended to fulfill that role, as Peter says:

Acts 1:20 “For it is written in the book of Psalms,
‘LET HIS HOMESTEAD BE MADE DESOLATE,
AND LET NO ONE DWELL IN IT’;
and,
‘LET ANOTHER MAN TAKE HIS OFFICE.’

Scripture tells us that Judas was deceived by Satan (John 13:2), he was indwelled by Satan (John 6:71), He betrayed Christ (Matt 26:25), he willingly chose to give up his apostleship to serve the devil (Acts 1:25), he later felt remorse for his sin (Matt 27:3), and he died a dishonoring death in keeping with his wicked actions (Acts 1:18).