St. Thomas the Apostle

St. Thomas (the name means "Twin")
Was out when the others were in.
It would have been best
If he'd stayed with the rest.
He appears only as a name on a list of apostles in the Synoptic Gospels, but he is mentioned in a few memorable passages in the Gospel of St. John.

Following the death of Lazarus, Jesus prepares to go to him in Bethany, a few miles from Jerusalem -- dangerously close for someone as unpopular with the religious leaders as He is. Thomas, in a moment of bravery not often expressed or acted upon by the Apostles before Pentecost, rallies the others to stay by their Master come what may:
Then therefore Jesus said to them plainly: Lazarus is dead. And I am glad, for your sakes, that I was not there, that you may believe: but let us go to him. Thomas therefore, who is called Didymus, said to his fellow disciples: Let us also go, that we may die with him. (John 11:14-16)
Later, with the acuity typical of the Twelve in the Gospels, Thomas misconstrues Jesus' reference to His death and resurrection. Thomas's question, easy to smile at in hindsight, provides Jesus an opportunity to teach one of the most profound and difficult truths of His ministry:
And if I shall go, and prepare a place for you, I will come again, and will take you to myself; that where I am, you also may be. And whither I go you know, and the way you know. Thomas saith to him: Lord, we know not whither thou goest; and how can we know the way? Jesus saith to him: I am the way, and the truth, and the life. No man cometh to the Father, but by me. If you had known me, you would without doubt have known my Father also: and from henceforth you shall know him, and you have seen him. (John 14:3-7)
Of course, St. Thomas is best remembered for being absent from the Upper Room the first time Jesus appeared to His disciples after His Resurrection.
Now Thomas, one of the twelve, who is called Didymus, was not with them when Jesus came. The other disciples therefore said to him: We have seen the Lord. But he said to them: Except I shall see in his hands the print of the nails, and put my finger into the place of the nails, and put my hand into his side, I will not believe. And after eight days again his disciples were within, and Thomas with them. Jesus cometh, the doors being shut, and stood in the midst, and said: Peace be to you. Then he saith to Thomas: Put in thy finger hither, and see my hands; and bring hither thy hand, and put it into my side; and be not faithless, but believing. Thomas answered, and said to him: My Lord, and my God. Jesus saith to him: Because thou hast seen me, Thomas, thou hast believed: blessed are they that have not seen, and have believed. (John 20:24-29)
This Gospel passage is read during Mass every year on the Second Sunday of Easter
St. Thomas is believed to have gone to India to preach the Gospel. Christians who trace their faith back to his mission live in Malabar, on the western coast of India, to this day. (See the Catholic Encyclopedia for an article on the St. Thomas Christians for more information.) There are reports that St. Thomas was slain by a spear while praying on a hill in Mylapur, near Madras on the east coast of India. His remains are said to have been buried there, and afterwards transported to the city of Edessa, in Mesopotamia, where confirmed reports of relics claimed to be his exist from the Fourth Century. (July 3, St. Thomas's feast in the Roman Calendar, is the date on which the Edessans celebrated the translation of the relics with "a great festival.") After eight hundred years, the relics were transported to the West, and now rest in Ortona, Italy.

I've heard two stories to explain St. Thomas as patron saint of builders. According to the first, he built a church with his own hands. According to the second, and more colorful, he offered to build a palace for an Indian king that would last forever. The king gave him money, which he gave to the poor. Asked to show his progress, St. Thomas explained that the palace he was building was in heaven, not on earth.