Cyclopentadienyl can refer to

• Cyclopentadienyl anion, or cyclopentadienide, [C
  ₅H
  ₅]⁻
  
  • Cyclopentadienyl ligand
• Cyclopentadienyl radical, [C
  ₅H
  ₅]^•
• Cyclopentadienyl cation, [C
  ₅H
  ₅]⁺
  

• Pentadienyl