Yoshiki Hayashi (born November 20, 1965, in Tateyama, Japan) is a musician, songwriter and producer. Throughout his professional career usually referred to by his given name only, he is primarily known for co-founding the popular rock band X Japan, for which he plays drums and piano, along with writing most of the music. He is currently involved with the supergroup S.K.I.N..

Yoshiki formed X Japan with vocalist Toshimitsu "Toshi" Deyama in 1982. Four years later, he founded his own independent label, Extasy Records, in order to issue the band's music. Their breakthrough came in 1989 with the release of the Blue Blood album. After three more albums and several tours, the group broke up in 1997 but releases of arranged material and reissues continue until today.

After X Japan disbanded, his next major endeavor was expected to become Violet UK, but the release of a debut album has since been postponed repeatedly. Beside a symphonic concert performed in 2002 and released on DVD in 2005 (which contained arrangements of old X Japan songs along with music supposedly created for Violet UK), no major publication of the project has yet surfaced.

In 2007, X Japan reunited. On October 22, 2007 they appeared together for the first time in over 10 years at a public filming of the promotion video for their new single "I.V." which was created for the movie Saw IV.