If you are looking for genuine *splendid* sarcasm:  
**One of the [beautiful people][1]**: wealthy or famous people whose lifestyle is usually expensive and well-publicized.

If you were to say "He thinks he's one of the beautiful people", you mean he puts himself in a class where (*the little*) people are expected to fawn over him and that he is faultless. (The faults of *beautiful people* are quickly overlooked by their adulators.)

(By the way, *beautiful people* can be taken positively, but it's easy to spot sarcasm with this phrase.)

There are also several words with a similar meaning (besides the ones already given) in common use. These all will universally be taken in negative terms:

**[priss][2]**: (back formation of *prissy*) An excessively proper person; one who is affectedly correct or prim. (where *proper* means conforming to established standards of behavior or manners; correct or decorous.)

**[prude][3]**:  a person who is excessively or priggishly attentive to propriety or decorum; especially :  a woman who shows or affects extreme modesty  

**[victorian][4]**: having the characteristics usually attributed to the Victorians, especially prudishness and observance of the conventionalities.(mildly negative)

**[self-righteous][5]**: (adjective) confident of one's own righteousness, especially when smugly moralistic and intolerant of the opinions and behavior of others. (To call someone a *righteous* person, on the other hand, generally is a positive or neutral term suggesting their religious nature.)


  [1]: http://www.merriam-webster.com/dictionary/beautiful%20people
  [2]: http://dictionary.reference.com/browse/priss?s=t
  [3]: http://www.merriam-webster.com/dictionary/prude
  [4]: http://dictionary.reference.com/browse/Victorian
  [5]: http://dictionary.reference.com/browse/self-righteous?s=t