Grassi is an Italian surname. Notable people with the surname include:
Alberto Grassi, Italian footballerAlex de Grassi, American guitaristBruno Grassi, Brazilian footballerCarlo Grassi, Italian cardinalCarlo Grassi, Italian partisanClaudio Grassi, Italian tennis playerDavide Grassi, Italian footballerErnesto Grassi, Italian philosopherFranz Dominic Grassi, German merchant with Italian descentGiacomo di Grassi, Italian fencing masterGiorgio Grassi, Italian architectGiovanni Antonio Grassi, Jesuit priest and President of Georgetown UniversityGiovanni Battista Grassi, Italian physician and zoologistGiuseppe Grassi, Italian politician, member of the Italian Liberal PartyGiuseppe Grassi, Italian cyclistGiuseppina Grassi, Mexican professional road cyclistGregorio Grassi, Italian Franciscan friar and bishopJosef Grassi, Austrian portrait and history painterLibero Grassi, Italian clothing manufacturer, killed by the MafiaLucas di Grassi, Brazilian race-car driverLuigi Grassi, Italian footballerMarco Grassi, Swiss footballerMitch Grassi, Member of the a cappella group Pentatonix (also a sassy little queen)Nicolò Grassi, also known as Nicola Grassi, Italian painter, active in a late-Baroque or Rococo styleOrazio Grassi, Italian Jesuit astronomer and mathematicianPaolo Grassi, Italian theatrical impresarioRaymond Grassi, Canadian former ice sledge hockey playerTullio Grassi, Swiss footballer