John T. Siomos (July 30, 1947 – January 16, 2004) was an American drummer who performed with Todd Rundgren, Mitch Ryder and the Detroit Wheels, Rick Derringer, Carly Simon, Mark "Moogy" Klingman, Buzzy Linhart and Frampton's Camel.

[1] Siomos was born in Chicago, son of Nick and Susie (née Kollias).

[3][4] Siomos, also known as John Headley-Down, co-wrote and performed on the songs "Doobie Wah",[5] and the hit single "Do You Feel Like We Do" from that album.

[6][7] He also played drums on "Hello It's Me" and other songs on Todd Rundgren's gold album Something/Anything?.

He is buried in Elmwood Cemetery, River Grove, Illinois.