Victor Klemperer's diaries are a great place to start. He was a linguist at the University of Dresden, World War I veteran, and ardent German nationalist. He also happened to he Jewish. His diaries cover the entire period of the Third Reich. As an added bonus, his diaries go on past the end of the war and into the postwar period of Communist East Germany.

I Shall Bear Witness - The diaries of Victor Klemperer, 1933-1941
To The Bitter End - The diaries of Victor Klemperer, 1942-1945
The Lesser Evil - The diaries of Victor Klemperer, 1945-1959

Happy Reading.

So I'm not exactly sure what you're looking for but a good place to start might be Die Weiße Rose (The White Rose) by Inga Scholl. Inga Scholl was the sister of Hans and Sophie Scholl who with fellow student Willi Graf and some others less involved, distributed six anti-NSDAP flyers in Munich (42-43). They were executed in 1943.

Another famous dissenter is Georg Elser who tried to blow up Hitler in Munich in 1939 (unsuccessfully as Hitler left the venue before the bomb blew up). He was interred at Dachau and was supposed to have a special show-trial after the war. He was murdered (shot by an SS Officer without having been sentenced) only 20 days before the liberation of Dachau.

Claus Stauffenberg too tried to assassinate Hitler multiple times (although generally the attempts were cancelled because of various timing issues and the fact that he wanted to assassinate Goering and Himmler together with Hitler). Stauffenberg was caught after an unsuccessful attempt on Hitler's life and executed in 1944.

There were many other resistance movements though they were small and typically fairly ineffective, most made of of left-leaning youth groups or religious groups (catholics, protestants etc).

The problem was that in a state where speaking out against the regime is treason, it is a risk to your own life to do so and it is difficult to know whom to trust to organise a large scale resistance. Most either did not speak out (out of fear for themselves and crucially, their families) or fled Nazi Germany and spoke out from abroad.

The lack of public outcry has been debated and much discussed in public as well after the war. It can be considered that a significant culture shift took place, not only in Germany but world wide through education campaigns around the Holocaust and the idea that we must never let this happen again. In practice this is of course easier said than done and silence is still often the most common response to atrocities.

You may have heard the words of Martin Niemöller:

>     First they came for the Socialists, and I did not speak out—
>     Because I was not a Socialist.
>     Then they came for the Trade Unionists, and I did not speak out—
>     Because I was not a Trade Unionist.
>     Then they came for the Jews, and I did not speak out—
>     Because I was not a Jew.
>     Then they came for me—and there was no one left to speak for me.

Check out the works of Dietrich Bonhoeffer. Particularly Letters and Papers from Prison for some of his thoughts along these lines. He was a German pastor and a pacifist from a prominent family at the beginning of the WW2 era who strenuously objected to the rise of the Nazi party he even did espionage work for the resistance and was involved in the famous but unsuccessful July 20th 1944 plot to assassinate Hitler by planting a bomb at a staff meeting. Pretty far journey from pacifism.