Mai kawo sauyi a cikin al’umma shi ne mutum wanda ke aiki don kawo sauye-sauye a cikin al’umma don magance matsalolin zamantakewa ko rashin adalci. Masu gyara zamantakewar al'umma yawanci suna aiki don inganta rayuwar marasa galihu ko marasa galihu, kamar matalauta, mata, tsirarun kabilanci da kabilanci, ko ma'aikata. Suna iya ba da shawarar sauye-sauye a cikin dokoki, manufofi, ko ƙa'idodin zamantakewa don haɓaka mafi girman daidaito, adalci, da jin daɗin zamantakewa. Wasu fitattun misalan masu gyara zamantakewa sun haɗa da Mahatma Gandhi, Martin Luther King Jr., Susan B. Anthony, da Florence Nightingale.