Just for fun, let's focus on deception in the character of Juliet (because she isn't someone one would usually guess). Most of Juliet's deception stems from her desperation, but it doesn't quite begin that way.
The first time I can see deception is, ironically, in Juliet's "What's in a name" speech. Why deception? Because she is letting no one close to her know her thoughts, she is concealing them and deceiving everyone as a result. In short, she has become a traitor to the family through her love of Romeo when she admits that if Romeo "be but sworn my love, / And I'll no longer be a Capulet" (2.2.37-38). It's funny that Romeo is also deceiving Juliet at the same time by spying on her!
Juliet's deception becomes volatile only when her relationship with Romeo is threatened. After openly disagreeing with her parents on their decision for her to marry Paris, Juliet feigns obedience in order to calm them down (just enough for her to drink the poison):
I met the youthful lord at Lawrence's cell / And gave him what becomed love I might, / Not stepping o'er the bounds of modesty. (4.2.27-29)
Juliet's ultimate deception (that unfortunately doesn't work out) involves a physical deception as well. This deception is evident in the largest part when Juliet drinks the poison that will make her only seem dead. Her words reveal her desired deception as she bids her mother farewell for the last time with "God knows when we shall meet again" (4.3.15).
What is most interesting to me is that we tend to think of deception as a very negative quality; however, there is no doubt that audience members are rooting for Juliet to succeed in her deception by the end of the play. What a shame, huh? Then again, that's why it's a tragedy.