sentence: '' members ; current members daron malakian -- guitar , vocals ( 1994 -- present ) serj tankian -- lead and other vocals , occasional keyboards and rhythm guitar ( 1994 -- present ) shavo odadjian -- bass , backing vocal ( 1994 -- present ) john dolmayan -- drums ( 1997 -- present ) ; former members andy khachaturian -- drums ( 1994 -- 1997 ) ; occasional contributors arto tunçboyacıyan -- percussion , composition ( on toxicity : '' science '' and '' atwa '' .