The Rolling Stones
Richards uses a fuzz pedal for the iconic guitar riff in this song. The sitar-like sound comes from the fuzz on a Strat.
The track's defining timbre is Brian Jones' real Indian sitar, whose sympathetic strings give the melody its sustained metallic resonance. Richards and Jones support it with tightly strummed rhythm instruments, but detailed session settings and exact guitar models have not been reliably documented. Settings approximated around the confirmed sitar-led arrangement. Source: Guitar World's Keith Richards riff retrospective and Bill Wyman recording feature.