An Unfamiliar Yet Familiar Face...
"Knight Rider", like many shows of the day, was famous for re-using background actors over and over again. Today, we are going to focus on one person - a member of the show's crew named Harold "Hal" Frizzell.
You've seen him as the security guard in "White Bird":

As a man sitting on a bench in "Brother's Keeper":

As the cab driver in "Knight of the Drones":

As a curious onlooker in "Knight Strike":

...and so many other times!
Here's a bit more about Hal, from an October 1998 article, courtesy of EmergencyFans.com:
Harold Frizzell was born in Ashland, Kentucky. He moved to California in 1950. He was working in a factory when asked if he rode horses -- thus began his start in show business.
When the pilot of Emergency! was being filmed, Randy Mantooth encouraged him to work on the movie. Later, Bob Cinader invited him to stay with the show. He was Kevin Tighe’s double and played one of the ambulance attendants.
After the show ended he went on to work on such things as The Rebels and The Seekers and then did stunts on Knight Rider. He also worked heavily on Quantum Leap.
So, the next time you watch "Knight Rider", keep an eye out. You never know when Hal will pop up!