As an adjective:
* Contrary to popular belief, the earth is not flat.
* The evidence presented was contrary to the defendant's claims.
* Her actions were contrary to her usual behavior.
As a noun:
* He argued his point with great passion, but the evidence was clearly to the contrary.
* The investigation revealed the contrary of what was initially reported.
As an adverb:
* Contrarily, the weather forecast predicted sunny skies, but it rained all day.
* Contrarily, to what you might expect, the book was a huge success.
In a phrase:
* On the contrary, I think this is a great idea.
* To the contrary, I believe that this project has merit.
Remember to choose the correct form of "contrary" depending on the context of your sentence.