Common words:
* Quick
* Queen
* Quilt
* Quiet
* Question
* Quote
* Queue
* Quake
* Quark
* Quantity
* Qualify
* Quarrel
* Quarter
* Quest
* Quit
Less common words:
* Quagmire
* Quail
* Quandary
* Quarantine
* Quasar
* Quiche
* Quintet
* Quixotic
* Quotient
Proper nouns:
* Quebec
* Quetzalcoatl
* Quentin
* Queen Elizabeth
* Quidditch (from Harry Potter)
Other words:
* Aquamarine
* Equinox
* Sequoia
* Frequent
* Sequel
This is not an exhaustive list, but it gives you a good starting point.