Competitive inhibition is observed in all except:

Competitive inhibition occurs when the inhibitor binds reversibly to the same site that the substrate would normally occupy and, therefore competes with the substrate for that site. E.g., Inhibition of alcohol dehydrogenase by ethanol in methanol poisoning, Sulpha drugs for folic acid synthesis in bacteria and Inhibition of succinate dehydrogenase by malonate. 

Cyanide kills an animal by inhibiting cytochrome oxidase is an example of non-competitive inhibition.