A young Richard Dreyfuss guest stars as Rodney, a warlock who wants to marry Samantha. Hoping to disrupt the relationship between Sam and her husband, Darrin, Rodney transforms himself into a dog and invades the Stephens household. Using his own special brand of witchcraft, the "shaggy" Rodney plants the seeds of suspicion in Darrin's mind. Written by Bernard Slade, "Man's Best Friend" originally aired on May 12, 1966. ~ Hal Erickson, Rovi