We all know lots of people; we also all know lots of persons. Normally we use the term "person" as a synonym for "human beings," people like us. However we are also familiar with the idea that there are nonhuman persons, and humans who are not, or may not be persons or full persons. Nonhuman persons may include gods, demigods, ghosts, extraterrestrials, angels, and devils. They may also include animals, fictional and real, with special properties or characteristics. These will include Mickey Mouse and Donald Duck, Winnie the Pooh, Tarka the Otter, Willy the whale, and, perhaps, educated nonfictional primates, like Washoe and Sarah (Allen and Gardner 1969; Linden 1975). Human nonpersons or humans who are not fully fledged persons may include zygotes and embryos, or individuals who are "brain-dead," anencephalic infants, or individuals in persistent vegetative state. I shall explore these categories of persons and possible persons more fully below. For the moment it is enough to remember our relative familiarity with the idea of nonhuman persons and human nonpersons, whatever we feel about the existence of such individuals or the respectability of the terminology.