Jonathan Gilbert

Jonathan J. Gilbert (born April 28, 1967) is a former American television and film actor known for his role as Willie Oleson on the TV series "Little House on the Prairie".
Personal life.
Gilbert was born on April 28, 1967. He is the adopted son of actors Barbara Cowen (née Barbara Crane) and Paul Gilbert and the adopted brother of actresses Melissa Gilbert and Sara Gilbert.
In Melissa Gilbert's 2010 autobiography, "Prairie Tale", she said Paul took his own life in 1976 due to his suffering from constant pain. Barbara then married Harold Abeles, and together they had Sara Abeles, who changed her name to Sara Gilbert, even though she has no relation to Paul. 
In Melissa Gilbert's autobiography, she wrote that when Jonathan was in his early 20s, he moved away from California and she had no relationship with him since then, for reasons supposedly unknown to her. Her autobiography states that he is a stockbroker living in New York City.
Acting career.
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. Also in 1979, he was in the made-for-TV-Movie "The Miracle Worker" as Jimmy. He was in two out of the three made-for-television movies based on "Little House on the Prairie" series of books (Little House: Look Back to Yesterday" and "Little House: The Last Farewell").