The co-founder, songwriter, and vocalist for Jefferson Airplane (and later with Jefferson Starship) died last week at 76. You can see him in this clip, to the left of Grace Slick, playing tambourine and singing backup at Woodstock:
Balin Sings lead on Volunteers
Balin wrote and sings lead on Plastic Fantastic Lover
White Rabbit, also at Woodstock (Balin is not in this clip, but I couldn't resist)
Balin wrote Today and is singing lead at Monterrey Pop (despite the camera on Grace Slick)
Comin' Back to Me in 2014