 Gilbert is best known for his performance as Willie Oleson on the NBC TV series, "Little House on the Prairie", from 1974 to 1983.He is also one of only six actors on "Little House on the Prairie" to appear throughout the entire series, along with Melissa Gilbert, Katherine MacGregor, Richard Bull, Kevin Hagen, and Dabbs Greer.In 1979, Gilbert was in the made-for-television movie "The Little House Years" also as Willie Oleson.