Liver

Liver is a slightly special colour. It is sometimes viewed as a dilute but this is not quite correct. Rather, liver could be said to be a case of the eumelanin being modified into dark brown rather than black. Liver in dogs can be caused by three different genes (all on the B-locus), and while the shade can vary a lot between and within different breeds, the basic idea is always the same: The coat is a dark brown, with a flesh-coloured nose and amber or light brown eyes. There cannot be any black anywhere on a liver dog.

A red dog can have liver pigment instead of black. Then it is often called a liver red. It should be noted, though, that a liver red dog does not have a liver coat. Rather, it has a "normal" red coat, but with liver eumelanin rather than black.
Liver can also come in all patterns that black can, such as merle (red merle, ginger merle), sable, tanpoint etc.

A dark liver (the shade of the coat can vary between and within breeds, and is dependant on the coat type) english springer spaniel

A liver grizzle siberian husky. Note how the lighter undercoat makes the colour look paler.

Liver red ibizan hound