Michael Landon, who was 5’9″ tall, was reportedly self-conscious about his height when he appeared on Little House on the Prairie. And it has been reported on multiple occasions that he wore 4″ lifts inside the boots he wore on the show, in order to appear taller, and more specifically, to be the tallest person in a scene.
In his earlier television show, Bonanza, he also wore 4″ lifts in his boots, as both his primary co-stars, Lorne Greene and Dan Blocker, were much taller than him.
In some episodes, it is clear that he has lifts in his boots, when you see where the ankle hits in the boots.