Dave

 is Darrin's best friend and drinking buddy.

After Darrin discovers his new bride Samantha is a witch, he confides in Dave about his worries and concerns. Dave does not really hear him though because he is waxing rhapsodically about marriage.

Episodes

 * And Then There Were Three
 * A Change of Face
 * Eye of the Beholder
 * The Girl With the Golden Nose
 * I, Darrin, Take This Witch, Samantha
 * If They Never Met
 * Red Light, Green Light
 * A Very Special Delivery

Trivia
The only time Dave has a substantial role is in the first season episode, Red Light, Green Light, where we discover he is a local councilman. In all other appearances, he is used in short gag scenes at bars where Darrin explicitly talks about his troubles with Samantha and witchcraft while Dave is in too much of a hurry to listen closely.