Judge of the living and the dead is a name of Jesus (Yeshua‘) in the New Testament. God appointed Jesus to that role. When Jesus returns, He will judge those who are still alive as well as those who have already died.
Judge of the living and the dead in Greek:
Kritēs zōntōn kai nekrōn
Strong’s Concordance numbers: 2923, 2198, 3499
Bible reference: Acts 10:42
He commanded us to preach to the people and to testify that he is the one whom God appointed as judge of the living and the dead. (Acts 10:42 NIV)
The KJV has Judge of the quick and the dead in this verse.
Similar names for God are Righteous judge, Judge of all, Judge of the earth, Judge of Israel, God of justice, Our lawgiver, and, in the New Testament, Righteous Judge. He is also called simply, the Judge.