William Last Name Unknown
From Shotgun Shuffling
We don't know a lot about William yet. Not even his last name. What we do know is generally in relation to Ginger.
First comic appearance was during Thanksgiving dinner before Black Friday shopping in comic All Right Ramblers.
In the first plot B arc, we see from Rosemary's memories that William and Ginger were high school sweethearts and that there had been some conflict regarding their relationship. For reference, see comics 20/20, 20/20 Part III, and The War at Home (originally Patreon-only but now posted on main site).