O = Oh

http://nfs.sparknotes.com/romeojuliet/page_80.html

JULIET
O Romeo, Romeo! Wherefore art thou Romeo?
Deny thy father and refuse thy name.
Or, if thou wilt not, be but sworn my love,
And I’ll no longer be a Capulet.

JULIET
(not knowing ROMEO hears her) Oh, Romeo, Romeo, why do you have to be Romeo? Forget about your father and change your name. Or else, if you won’t change your name, just swear you love me and I’ll stop being a Capulet.





http://nfs.sparknotes.com/tempest/page_188.html
MIRANDA
Oh, wonder!
How many goodly creatures are there here!
How beauteous mankind is! O brave new world,
That has such people in ’t!

MIRANDA
How amazing! How many wonderful creatures there are here! Mankind is so beautiful! Oh, what a wonderful new world, that has such people in it!