Wilhelm Rudolph Fittig (6 December 1835 – 19 November 1910) was a German chemist.
Fittig discovered the pinacol coupling reaction, mesitylene, diacetyl and biphenyl.
He studied the action of sodium on ketones and hydrocarbons.
He discovered the Fittig reaction or Wurtz–Fittig reaction for the synthesis of alkylbenzenes, he proposed a diketone structure for benzoquinone and isolated phenanthrene from coal tar.
He discovered and synthesized the first lactones and investigated structures of piperine naphthalene and fluorene.