Calabasas (California): Actor Richard Bull, best known for his performance as Nels Oleson in 'Little House on the Prairie', passed away here aged 89.
Bull died on February 3 but the cause of death has not been revealed yet, reports a website.
His former co-star Melissa Gilbert, who played protagonist Laura Ingalls Wilder in 'Little House on the Prairie', tweeted her condolences along with a photo of him.
"This man will be missed", the 49-year-old actress posted.
"Goodbye Richard working with you was such a joy but nearly as joyful as being your friend," she added.
Bull is survived by his actress-wife Barbara Collentine.