Caeca invidia est - Envy is blind. (Livy)
Caeci caecos ducentes - Blind are led by the blind. Leaders are not more knowledgeable than the ones they lead
Caeli enarrant gloriam Dei - The heavens declare the glory of God

Caelum non animum mutant qui trans mare currunt

They change the sky, not their soul, who run across the sea. (Horace)

Caelum videre iussit, et erectos ad sidera tollere vultus - He bid them look at the sky and lift their faces to the stars. (Ovid)
Caesar si viveret, ad remum dareris - If Caesar were alive, you'd be chained to an oar
Camera obscvra - Hidden room - an early photographic or painting technique utilizing optical pinholes
Canis meus id comedit - My dog ate it
Canis timidus vehementius latrat quam mordet - A timid dog barks more violently than it bites. (Curtius Rufus)
Capillamentum? Haudquaquam conieci esse! - A wig? I never would have guessed!