Death is the permanent and inevitable ending of a living organism which is commonly caused by aging, terminal diseases, homicide, etc. Death is a common theme throughout the series in each episode where any food or object, that Orange encounters, is subjected to it.
Knife: Knife is the most common cause of death of each food that Orange meets. Usually, Knife will only appear if Orange tries to warn any food product, blurting out the weapon-in-use, such as "Knife!". Despite that, Knife is actually a nice person, as revealed in No More Mr. Knive Guy, and is only used to slaughter against his will by his user, Daneboe.
Squash: Squash is a common cause of death, in which he will drop from out of nowhere and crush the victim to death beneath his backside. Like Knife, Squash does not intend to harm anyone - he is very timid and is horrified at the deaths he causes, but it is unknown why he drops out of nowhere.
Dane Boedigheimer: Creator, Dane Boedigheimer, is also a minor character and antihero of the show. He kills many food characters by simply preparing them to be eaten, or if applicable, devouring them instantly
Explosions: Usually caused by TNT or some other explosive substance, many characters have died from exploding.
Other: There are numerous alternative causes of death throughout the series, ranging from cheese graters, to falling objects, to evil robots.
Continuity and Non-Permanent Deaths
While the deaths of many characters that Orange and his friends encounter are permanent, there are many rare instances where some characters come back after being killed. An example of this is Grapefruit, in Passion of the Fruit, Grapefruit gets killed when he suddenly gets sliced up by a knife and served as a treat, however, he is revived in the form of Frankenfruit in the episode of the same name, albeit having been reduced to basically his normal self again while he survived from being attacked by the Halloweenie and since then, became a recurring character in the series.