An individual named the Adversary appears in Job 1:6-12 (NJPS):
One day the divine beings presented themselves before the Lord, and the Adversary came along with them. The Lord said to the Adversary, “Where have you been?” The Adversary answered the Lord, “I have been roaming all over the earth.” The Lord said to the Adversary, “Have you noticed My servant Job? There is no one like him on earth, a blameless and upright man who fears God and shuns evil!” The Adversary answered the Lord, “Does Job not have good reason to fear God? Why, it is You who have fenced him round, him and his household and all that he has. You have blessed his efforts so that his possessions spread out in the land. But lay Your hand upon all that he has and he will surely blaspheme You to Your face.” The Lord replied to the Adversary, “See, all that he has is in your power; only do not lay a hand on him.” The Adversary departed from the presence of the Lord.
It's hard not to draw a straight line to the serpent in Genesis 3:1-4 (NJPS):
Now the serpent was the shrewdest of all the wild beasts that the Lord God had made. He said to the woman, “Did God really say: You shall not eat of any tree of the garden?” The woman replied to the serpent, “We may eat of the fruit of the other trees of the garden. It is only about fruit of the tree in the middle of the garden that God said: ‘You shall not eat of it or touch it, lest you die.’” And the serpent said to the woman, “You are not going to die, 5but God knows that as soon as you eat of it your eyes will be opened and you will be like divine beings who know good and bad.”
But while they both seem to be intent on interfering with God's design, there are many differences between the two beings:
The serpent is a beast created by God yet the Adversary seems to be a divine being.
The serpent speaks to Eve alone yet the Adversary speaks directly with God.
God curses the serpent yet no mention is made of consequences for the Adversary.
So should these two characters be identified with each other or are they different beings altogether.