Carel Struyken has returned to the new incarnation of 'Twin Peaks' as The Giant (although he was listed in the end credits as "????????") in what most likely will be the 2017 Toobits Award winner for Best Episode Any Genre ("Part 8" or "Gotta Light?" if you need something more specific.) Although it was all very confusing, I got the sense that The Giant was instrumental in combating the forces of the Black Lodge who were unleashed by the 1945 A-Bomb test and who then went on to create BOB.
Previously, The Giant had appeared in at least five episodes of the original show's second season. That was back in 1990, but could we have seen The Giant earlier in the Toobworld Timeline?
Carel Struyken - The Giant
Actually, the name of his character was given, but whoever edited this page for the IMDb failed to do the research. The Giant of "Fairytale Theater" was named Frank Lydaczech, who spoke with Luther about the concept of size.
Standing at 7 feet tall, the Dutch actor gets many of those roles in which height plays a key role. But I'm not sure we can conflate both roles to be the same person, even if Struyken is the actor in both and they both share the same generic title.
The theory might have been viable if 'Twin Peaks' had never come back and so we didn't see that The Giant was already some kind of cosmic being back in the 1950s. Although I suppose he could have made himself a tangible humanoid on Earth Prime-Time, with the alias of Frank Lydaczech in order to make contact with Luther at St. Eligius Hospital. We saw him collapse in the snow at the end of the episode with the intimation that he had died, but it could have been that he slipped into unconsciousness. We just never saw a follow-up to his story, one way or the other.
If he was The Giant of 'Twin Peaks', it could be that he could not survive under the conditions of the main Toobworld's plane of reality. Since we never saw a follow-up, perhaps "Lydaczech" transferred his essence back to the alternate dimension from which he came.
There are those who buy into the idea that all of 'St. Elsewhere' took place in the mind of Tommy Westphall, who was autistic. I'm not one of those people. The final scene of the series was part of Tommy's imagination, but everything else leading up to that was "Realiteevee". Besides, it's not like Tommy could have dreamed up The Giant as being from 'Twin Peaks' since that show wouldn't hit the airwaves until 1990.
I'm dismissing that idea outright, but I'm not going to declare one way or the other that we could have seen the 'Twin Peaks' Giant in 'St. Elsewhere'. 'Twin Peaks' in ongoing and Mr. Struyken's role may have more to offer us. I think that considering the wild artistic vision of David Lynch, anything may yet happen.
But when the time comes when I could make a deliberate claim, I think I would have to rule in favor of the blended realm of Toobworld.