American Dad! and is voiced by Seth MacFarlane. Out of all the voices he's done in both Family Guy and American Dad!, MacFarlane says that Stan's voice is the most exhausting. It has been noted on DVD special features that Stan's voice is based on the announcers of 1950s American anti-communist propaganda films. He is similar to the title character from the cult 80s show Sledge Hammer, who also had a weird habit of talking to his gun, as Stan does.
Stan has worked for the Central Intelligence Agency since the 80s, as a field agent and weapons expert under Deputy-Director Avery Bullock. In this role his work has included the interrogation of possible terrorists. Stan is always on alert for terrorist activity, at work, and in his home life.
At some point in Stan's childhood, someone gave him bad advice about sex, leading to Stan's belief that masturbation would lead to hair growing on his palms and his eyes melting, a belief which Stan almost passed on to his son. This belief led to a life-long love of hobbies, including gun cleaning and wood burning. Stan also collects commemorative plates from the Franklin Mint.
In "Stan's Food Restaurant", it's revealed that he lived in or near Philadelphia at the time his father left him and that he was molested by Father Roy, his priest. Although on further reflection he thinks he may have seduced Father Roy. In "The Best Christmas Story Never", Stan is taken back in time to his boyhood home by Michelle, the Spirit of Christmas Past, after which he travels to the New York of 1970.
Stan attended John DeLorean High School in the late 1970s and early 1980s. A very unpopular student, he got pranked by the popular students while at the prom by being crushed by falling pigs in "It's Good to Be the Queen".
Stan was scrawny and had horrible acne, which caused him to be nicknamed "The Penis". It is revealed in "Chimdale" that in an effort to get rid of his acne, he took part in testing of an experimental acne treatment. The treatment caused all his hair to fall out, and he has worn a toupee ever since. Up until this episode, he didn't think anyone knew. The family told him that it was obvious.
Stan recounts in "Francine's Flashback" that he met his future wife Francine while she was hitch-hiking and Stan gave her a ride. As he was driving, he accidentally ran over a raccoon, which he shot to put it out of its misery, and Francine thought it was the most compassionate act she had ever seen. They got married later that same year. Stan's father, Jack Smith, wasn't able to attend the wedding so he had a fake father, Grandpa Smith, come to the wedding and pose as his real father for 20 years in "Con Heir".
In "Black Mystery Month" it is revealed Stan is a part of the Illuminuti, an organization trying to keep a peanut butter conspiracy secret.