In the original first season intro his Grandpa is shown with him and the rest of his family. Funny thing is I can't remember his Grandpa appearing in a single episode. Green Goblin is great! https://www.youtube.com/watch?v=t1L4ZuaVvaw
This makes absolutely no sense. I have always remembered Arthur's maternal grandfather, "Grandpa Dave" in the opening credits. Thora is Arthur's paternal grandmother. But this does not answer what happened to Dave's wife and Thora's husband. I assume that their spouces have died long before Arthur was even born or perhaps both couples got divorced and married again (perhaps to each other, resulting in everybody in The Read Family being married to their in-laws. This embarrassment to The Read Family is why they don't ever talk about them.)
Grandpa Dave appeared in many episodes. He doesn't appear as often as Thora because he lives in a very rural area by himself, trying to take care of a neglected farm. One episode involved Grandpa Dave being sick and had to move in with them, and another about Alzheimer's. In each major story line Grandpa Dave ages horribly.
Grandpa Dave is voiced by A.J. Henderson, the same voice for Ed Crosswire.
Wasn't Arthur named for his paternal grandfather? I feel like Thora mentioned that in "Arthurs Chicken Pox" Dora Winefred sounds like it could have come from a grandparent as well. Maybe an adaption of Thora and then Winefred for Jane's mom.
Next time I'll just die on the river so Sam can see a waterfall.
His paternal grandfather is missing. It is possible he died many years before Arthur was born or Thora & David's father didn't ever get married. (or he embarrassingly married Jane's mother.)
I always assumed that Jane's maiden name is Winifred, meaning that it is very likely that Grandpa Dave's last name is Winifred.
While Thora is shown to have three brothers, It seems like David and Jane are both only children??
I wonder if they will make an episode about grandpa Dave or any other elderly character dying. There are episodes with gloomy themes already, for example; the cafeteria lady getting cancer and D.W.'s pet bird (Spanky) dying. I wonder if the writers think it would be too much for kids.