500D may refer to:

• Canon EOS 500D - a camera
• MD Helicopters MD 500 - aka Hughes 500D
  • MD 500 Defender - a military version

• Cauchy equation
• Cauchy formula
• Cauchy formula for repeated integration
• Cauchy Functional Equation
• Cauchy functional equation
• Cauchy Goursat
• Cauchy-Goursat
• Cauchy-hadamard theorem
• Cauchy-Hadamard Theorem
• Cauchy inequality
• Cauchy initial value problem
• Cauchy integral test
• Cauchy integral theorem
• Cauchy-Kovalevskaya theorem
• Cauchy-Kovalevski theorem
• Cauchy-Kowalevsky theorem
• Cauchy-Kowalewski theorem
• Cauchy-Lagrange identity
• Cauchy-Lipschitz theorem
• Cauchy matrix
• Cauchy mean theorem
• Cauchy noise
• Cauchy-Peano theorem
• Cauchy principal part
• Cauchy principal part integral