Found this. They're in alphabetical order, and one Irish poet was born in 1796 and died in 1906!

(I have to admit I only recognize a handful of the names - mostly the ones who were on my lists. Oddly, certain living writers - such as historian Bernard Weisberger and poet Edward Lueders - are not listed, though other living writers are. They're shaded in blue.)

https://en.wikipedia.org/wiki/List_of_centenarians_(authors,_editors,_poets_and_journalists)

And I also stumbled, elsewhere, on the story of Viola Fletcher, now aged 109, who is the oldest living survivor of the Tulsa Race Massacre. (She was 7 at the time.) Since her memoir was published in June, that makes her (reportedly) the world's oldest living author.

https://en.wikipedia.org/wiki/Viola_Fletcher

And here are the centenarian children's writers/illustrators (in chronological order).

I found ten other names in Google, including four pretty famous names - but the others I didn't know at all. Only one was born before 1900.

(I'm also leaving out those people who are reportedly alive; you can see them on my semi-annual list if you want.)

Catherine Woolley 1904-2005 (A Room for Cathy, 1956)

Ellen Tarry 1906-2008 (journalist/biographer)

Jeannette Eyerly 1908-2008 (YA novelist, 1960s-1980s)

Margaret Rau 1908-2014 (Holding Up the Sky: Young People in China, 1983)

Dana Faralla 1909-2014 (The Wooden Swallow, 1966)

Michio Mado 1909-2014 (Japanese poet & 1994 Hans Christian Andersen Medalist)

Eleanor Means Hull 1913-2013 (social worker and YA novelist, 1949-1984)

Sheilah Beckett 1913-2013 (Canadian-born writer/illustrator, The Twelve Dancing Princesses, 1954)

Jean Fritz 1915-2017 (historical biographer and 1986 Hans Christian Andersen Award finalist)

Beverly Cleary 1916-2021 (author of Ramona the Pest, 1968, & 1984 Hans Christian Andersen Award finalist & Newbery Medalist)

Ann Tompert 1918-2019 (Grandfather Tang's Story: A Tale Told with Tangrams, 1990)

Lyn Cook 1918-2018 (Canadian YA novelist: The Hiding Place, 1990)

Joe Krush 1918-2022 (co-illustrator of The Borrowers by Mary Norton, 1952)

Fern G. Brown 1918-2021 (YA biographer & horse novelist)

Lee Kingman Natti 1919-2020 (Horn Book editor/designer/writer/Edgar nominee/Caldecott Honoree)

Felice Holman 1919-2023 (YA novelist: Slake's Limbo, 1974)

Jean Kenward 1920-2022 (British poet & author of Ragdolly Anna Stories, 1979-1987)

Leonard Kessler 1920-2022 (writer/illus. of Mr. Pine series & 200 more books)

Al Jaffee 1921-2023 (MAD cartoonist)

Dorothy M. Martin 1921-2022 (writer of Protestant mysteries & YA Peggy series, 1957-1976)