Celebrity Celebrity Deaths Celebrity Death Tributes Neil Patrick Harris Recalls His Late Doogie Howser, M.D. Costar James B. Sikking Having 'a Spark of Mischief in His Eyes' Harris remembered Sikking — who died at age 90 on July 13 — as "one of the kindest, wisest, funniest, and most generous people I’ve ever known" By Stephanie Wenger Stephanie Wenger Stephanie Wenger is a TV Writer/Reporter at PEOPLE. She joined the brand in 2021 as a digital news writer, covering stories spanning across the site's verticals. She previously contributed E! Online, Hollywood Life and Oscar.com. People Editorial Guidelines Published on July 15, 2024 03:10PM EDT Close James B. Sikking (left) and Neil Patrick Harris (center) on the set of 'Doogie Howser, M.D.' alongside costar Belinda Montgomery. Photo: ABC Photo Archives/Disney General Entertainment Content via Getty Neil Patrick Harris is remembering his Doogie Howser, M.D. costar James B. Sikking after his death. The 51-year-old actor — who played Sikking’s on-screen son on the ABC medical sitcom from 1989 to 1993 — shared his memories of working with the Emmy nominee in a heartfelt Instagram tribute. “Jim Sikking played my dad in Doogie Howser, MD, and was one of the kindest, wisest, funniest, and most generous people I’ve ever known,” Harris shared alongside a photo of Sikking. Belinda Montgomery, James B. Sikking (center) and Neil Patrick Harris on 'Doogie Howser, M.D.'. ABC Photo Archives/Disney General Entertainment Content via Getty Paying Tribute to the Celebrities Who Have Died in 2024 He called the actor “a true professional,” adding, “He treated everyone with respect, taught me countless lessons, yet always had a spark of mischief in his eyes. It was an absolute honor to be his son. My condolences to his actual family for their loss. #RIP” PEOPLE confirmed on Sunday, July 14, that Sikking died at the age of 90. According to his publicist, Cynthia Synder, the Hill Street Blues actor died "peacefully at his Los Angeles home surrounded by family." The cause of death was dementia. Sikking is survived by his wife of 61 years, Florine, his son Andrew, daughter Dr. Emily Sikking (Mallory ‘Chip’ Milam), and four grandchildren. 'Doogie Howser M.D.' cast James B. Sikking, Neil Patrick Harris and Belinda Montgomery. ABC Photo Archives/Disney General Entertainment Content via Getty Images Never miss a story — sign up for PEOPLE's free daily newsletter to stay up-to-date on the best of what PEOPLE has to offer, from juicy celebrity news to compelling human interest stories. In addition to Doogie Howser, M.D., Sikking was best recognized for playing Lt. Howard Hunter, the leader of the precinct’s Emergency Action Team, on Hill Street Blues from 1981 to 1987. The actor also appeared on shows included The Pelican Brief, Fever Pitch, Made of Honor and The Closer.