To the downvoters: sure, Wikipedia is not the canonical source (that would be IANA's list[0]). But Wikipedia mostly gets it right and also lists some of the "non-standard but can be encountered in the wild" ones.

I actually prefer the Wikipedia page[1] exactly because it includes more than just the canonical subset. For example, 451 is not yet official, but pretty much as close as you can get to a standard without having an actual standard (well, there's a draft).

[0]: http://www.iana.org/assignments/http-status-codes/http-statu... [1]: http://en.wikipedia.org/wiki/List_of_HTTP_status_codes