The Apostle Paul had a possible near-death experience described in II Cor 12:1-4:
"It is not expedient for me doubtless to glory. I will come to visions and revelations of the Lord.
I knew a man in Christ above fourteen years ago, (whether in the body, I cannot tell; or whether out of the body, I cannot tell: God knoweth, such an one caught up to the third heaven.
And I knew such a man, (whether in the body, or out of the body, I cannot tell: God knoweth, How that he was caught up into paradise, and heard unspeakable words, which it is not lawful for a man to utter."
This does sound like a conventional NDE that we hear of today.
I'm of the opinion that we are concious after death, for a number of biblical reasons. The aforementioned Paul suggests this:
"We are confident, I say, and willing rather to be absent from the body, and to be present with the Lord." - II Cor 5:8
"According to my earnest expectation and my hope, that in nothing I shall be ashamed, but that with all boldness, as always, so now also Christ shall be magnified in my body, whether it be by life, or by death.
For to me to live is Christ, and to die is gain.
But if I live in the flesh, this is the fruit of my labour: yet what I shall choose I wot not. For I am in a strait betwixt two, having a desire to depart, and to be with Christ; which is far better:" - Philippians 1:20-23
Secondly, there are several examples of people who are concious beyone the grave:
"Now Samuel was dead, and all Israel had lamented him, and buried him in Ramah, even in his own city. And Saul had put away those that had familiar spirits, and the wizards, out of the land." - I Samuel 28:3
"And Saul disguised himself, and put on other raiment, and he went, and two men with him, and they came to the woman by night: and he said, I pray thee, divine unto me by the familiar spirit, and bring me him up, whom I shall name unto thee.
And the woman said unto him, Behold, thou knowest what Saul hath done, how he hath cut off those that have familiar spirits, and the wizards, out of the land: wherefore then layest thou a snare for my life, to cause me to die?
And Saul sware to her by the LORD, saying, As the LORD liveth, there shall no punishment happen to thee for this thing.
Then said the woman, Whom shall I bring up unto thee? And he said, Bring me up Samuel.
And when the woman saw Samuel, she cried with a loud voice: and the woman spake to Saul, saying, Why hast thou deceived me? for thou art Saul.
And the king said unto her, Be not afraid: for what sawest thou? And the woman said unto Saul, I saw gods ascending out of the earth.
And he said unto her, What form is he of? And she said, An old man cometh up; and he is covered with a mantle. And Saul perceived that it was Samuel, and he stooped with his face to the ground, and bowed himself. And Samuel said to Saul, Why hast thou disquieted me, to bring me up?..." - I Samuel 28:8-15
There is no reason not to believe that this was truly the spirit of Samuel, for he correctly prophesizes Saul's and his son's deaths.
Then we have the Transfiguration:
"And it came to pass about an eight days after these sayings, he took Peter and John and James, and went up into a mountain to pray.
And as he prayed, the fashion of his countenance was altered, and his raiment was white and glistering.
And, behold, there talked with him two men, which were Moses and Elias:
Who appeared in glory, and spake of his decease which he should accomplish at Jerusalem.
But Peter and they that were with him were heavy with sleep: and when they were awake, they saw his glory, and the two men that stood with him.
And it came to pass, as they departed from him, Peter said unto Jesus, Master, it is good for us to be here: and let us make three tabernacles; one for thee, and one for Moses, and one for Elias: not knowing what he said.
While he thus spake, there came a cloud, and overshadowed them: and they feared as they entered into the cloud.
And there came a voice out of the cloud, saying, This is my beloved Son: hear him.
And when the voice was past, Jesus was found alone. And they kept it close, and told no man in those days any of those things which they had seen." - Luke 9:28-36
These are two prophets who have been dead for several hundred years. (Well, Elijah actually got taken up to heaven in a chariot of fire, but neverthless, he had been absent for centuries. Certainly, Moses was dead.)