Otto Wels (September 15 1873 - September 16 1939) was the chairman of the Social Democratic Party of Germany (SPD) from 1919 and a member of parliament from 1920 to 1930.

On March 23, 1933 the Berlin-born Wels was the only member of the Reichstag to speak against Hitler's enabling act. During that speech he said, "You can take our lives and our freedom, but you cannot take our honour". All 94 SPD members of parliament voted against the act; the rest of the Reichstag voted in favour.

Some weeks before the banning of the SPD by the Nazis, Wels went into exile. He built up the expatriate SPD, first in Prague, then in the Saarland and finally in Paris, where he died in 1939.