Me and my fiance just left the Uk 2 weeks ago after staying for 6 months. We rented a place for 6 months in both our names. We are about to marry within the week in Germany where I am a citizen. She is from the USA. We want to then go back to the UK after we are wed and have all the official documents etc. I don't need a visa to visit the UK but will she? Or is proof of our marriage and her passport sufficient enough to at least let us both in without a problem.
The other (now deleted) answer was wrong. Your wife can benefit from free movement even without an EEA family permit. The UK's implementing regulations are the Immigration (European Economic Area) Regulations 2016.
Regulation 7 defines "family member" to include a spouse. Regulation 11(2)(b) is perhaps the reason for the assertion in the other answer that your wife needs an EEA family permit to benefit from free movement:
(2) A person who is not an EEA national must be admitted to the United Kingdom if that person is—
(b) a family member of an EEA national, a family member who has retained the right of residence, a person who meets the criteria in paragraph (5) or a person with a right of permanent residence under regulation 15 and produces on arrival—
(i) a valid passport; and
(ii) a valid EEA family permit, residence card, derivative residence card or permanent residence card.
However, that conclusion overlooks regulation 11(4), in particular 11(4)(b):
(4) Before an immigration officer refuses admission to the United Kingdom to a person under this regulation because the person does not produce on arrival a document mentioned in paragraph (1) or (2), the immigration officer must provide every reasonable opportunity for the document to be obtained by, or brought to, the person or allow the person to prove by other means that the person is—
(b) a family member of an EEA national with a right to accompany that EEA national or join that EEA national in the United Kingdom;
The critical language there is, of course, "allow the person to prove by other means." To do that, you should bring your marriage certificate and any other evidence that you might submit with an EEA family permit application. If you or your wife are inclined to worry or stress, it might be a good idea to apply for the EEA family permit ahead of time even though she doesn't need it.
The other answer asserted incorrectly that your wife would be bound by the immigration rules without a family permit. But regulations 13 through 15, which concern the right of residence, do not make any mention of the EEA family permit.
Furthermore, if your wife should be admitted with a stamp saying "leave to enter for six months, employment and recourse to public funds prohibited" then she should take note of Schedule 3, paragraph 1, which says that the restrictions imposed by that stamp do not have effect while she is in the UK with you:
Leave under the 1971 Act
- Where a person has leave to enter or remain under the 1971 Act which is subject to conditions and that person also has a right to reside under these Regulations, those conditions do not have effect for as long as the person has that right to reside.