*Ar for any aromatic substituent (Ar is also the symbol for the element argon.  However, argon is inert under all usual conditions encountered in organic chemistry, so the use of Ar to represent an aryl substituent never causes confusion.)
*Het for any heteroaromatic substituent
*Bn or Bzl for the benzyl group (not to be confused with Bz for benzoyl group; However, old literature may use Bz for benzyl group.)
*Dipp for the 2,6-diisopropylphenyl group
*Mes for the mesityl group
*Ph, Φ, or φ for the phenyl group (the use of phi for phenyl has been in decline)
*Tol for the tolyl group, usually the para isomer
*Is or Tipp for the 2,4,6-triisopropylphenyl group (the former symbol is derived from the synonym isityl)
*An for the anisyl group, usually the para isomer (An is also the symbol for a generic actinoid element.  However, since the anisyl group is monovalent, while the actinides are usually divalent, trivalent, or even higher valency, ambiguity rarely, if ever, arises in practice.)
*Cp for the cyclopentadienyl group (Cp was the symbol for cassiopeium, a former name for lutetium)
*Cp* for the pentamethylcyclopentadienyl group
*Vi for the vinyl group (uncommon)