Moderatus of Gades was a philosopher from the 1st century CE, active in the Roman Empire. He was a Neopythagorean, part of a movement that revived and reinterpreted the teachings of the ancient Greek thinker Pythagoras. He came from Gades, modern-day Cádiz in Spain, a major port city in the Roman province of Hispania. Beyond this, the specific details of his life and education are not known from surviving records.

His importance rests on a single, lost work, often referred to as Pythagorean Lectures or Pythagorean Doctrines. This book survives only in fragments, which were quoted centuries later by Neoplatonist philosophers like Porphyry and Simplicius. These fragments show that Moderatus worked to systematize Pythagorean ideas, often blending them with concepts from Plato and Aristotle.

According to modern scholars, his main contribution was a metaphysical system that used numbers and principles to explain how a supreme, ineffable reality connects to the physical world. This framework is seen as an important step between early Pythagorean thought and the later, more developed emanation theories of Neoplatonism. He was also cited as an authority on the symbolic and mysterious sayings of the Pythagoreans. In this way, Moderatus served as a key bridge, preserving and transforming Pythagorean philosophy for later generations in the Roman world.