Full Tilt Ice Cream has several vegan ice cream options.
http://www.fulltilticecream.com/
The have several locations:
Ballard
5453 Leary Ave NW
Seattle, WA 98107
(206)297-3000
Columbia City
5041 Rainier Ave S
Seattle, WA 98118
(206)226-2740
University District
4759 Brooklyn Ave NE
Seattle, WA 98105
(206)524-4406
White Center
9629 16th Ave SW
Seattle, WA 98106
(206)767-4811