One of my favorite Herman faces is when Grandpa is trying to cure Herman's hiccups through hypnosis. His face at 8:15 is hilarious.
https://youtu.be/4jZQlw2qnbo

I love the part at 13:29 when he first sees the cartoon and he breaks into that silly grin. The only thing funnier than Herman stupefied might be Herman stupefied and simultaneously amused.

ROFL: 14:38 Lily nattering on while Johan looks stupefied

Don't forget Gwynne as Herman's alter ego, Johann. Talk about a vacant look.

In the John Doe Munster episode when Herman has amnesia, and the Lily adopts him and he acts like a little boy. He is still acting like a little boy until Eddie is trying to fly a his kite off the roof on that windy day. Then he sees Eddie about to fall off the roof. The expression on Gwynne's face turning from the little boy to serious Herman is priceless.

Yeah poor Herman, I think sometimes he was actually more lost and helpless than even Karloff's monster was!
"Life IS pain highness. Anyone who says differently is selling something".

Yeah the hand-shaking was great

I often find myself laughing hysterically at Gwynne's mannerisms and facial expressions.
The other day I was watching "If a Martian Answers, Hang Up" I busted a gut laughing when they cut to the scene where Herman is singing "My Mothers Eyes" into his Ham Radio.

Or when he shakes his hands rapidly when he's just accidentally broken or destroyed something. Only Gwynne could do that and not have it look spastic, but more befuddled.
I love when he would jump up and down when he was upset, yelling, "Darn darn darn DARN!"

A great facial actor. I don't know if they're too many better

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