Hair grass is a common name for several plants and can refer to:

• Agrostis hyemalis (winter bentgrass, ticklegrass)
• Agrostis scabra, "hair grass" (rough bent grass, winter bent grass, ticklegrass)
• Aira, hairgrass
• Aira caryophyllea, silver hairgrass
• Aira praecox, early hair grass
• Corynephorus canescens, grey hair-grass
• Deschampsia, hair grass
• Eleocharis acicularis, dwarf hairgrass
• Eleocharis parvula, "hairgrass" (dwarf spikerush, small spikerush)
• Koeleria glauca, Blue Hair Grass
• Koeleria macrantha, crested hair grass
• Koeleria vallesiana, Somerset hair grass
• Rostraria cristata, Mediterranean hair grass