Ruben is a Hebrew name from the Old Testament, sometimes called Reuben, especially in English speaking countries. For obvious reasons I will entirely ignore you silly people in this case!
As the book of Genesis tells us, Ruben is the oldest son of Jacob and Leah. Benjamin was the youngest, Joseph was Jacob's most favourite son. The name Ruben means "behold, a son", which is usually explained with his mother's words at his birth:
Jacob then consummated his marriage with Rachel also, and he loved her more than Leah.(...)
When the Lord saw that Leah was unloved, he made her fruitful, while Rachel remained barren.
Leah conceived and bore a son, and she named him Ruben, for she said, It means, 'The Lord saw my misery; now my husband will love me.'
Genesis, chapter 29.
Ruben was hardly an ideal role model for his younger brothers, however. His father cursed him for sleeping with one of his wives. Elsewhere, Ruben seems to have been a more positive force in the family. He picked mandrakes for his mother Leah to help her attract Jacob so that she could bear him more children. He prevented his brothers from killing Rachel's son Joseph out of jealousy, by urging them instead to throw Joseph into a pit and then was genuinely heartbroken when it was later discovered that Joseph was missing. And when Joseph, unrecognized by his brothers, demanded that they return to Egypt with Rachel's other son Benjamin, Ruben tried to persuade Jacob to allow Benjamin to go by saying that Jacob could kill Ruben's own sons if Benjamin did not return safely.
After the final reconciliation, Ruben would be the ancestor of one of the twelve tribes of Israel, the name God gave Jacob; his eleven brothers would found the others. At the reconciliation, Israel told his oldest son:
Thou art my firstborn, my might, and the beginning of my strength, the excellency of dignity, and the excellency of power:
Unstable as water, thou shalt not excel; because thou wentest up to thy father's bed; then defiledst thou it: he went up to my couch.
The tribe of Ruben was allotted land east of the Jordan River, provided the Rubenites would help the rest of Israel conquer the promised land west of the Jordan.