This is great fun. Ta Crash.
One of my favourite strips is Paul Temple who regularly exclaims, "By Timothy". This is a carry over from the radio shows.
And what about the Blackhawks? "Py Jimminy", "By Gar", "Sacre Bleu" and so on supposedly reflecting each nationality.
El Guerrero del Antifaz says "Maldicion" regularly.
Marvelman says "Holy Macaroni" an awful lot!
Dick Bos utters "Groote Hemel" Good Heavens.
Groote means great, large(big), high (as in position or rank), or exalted. In context, I would consider it as "High Heaven" or "Great Heaven". The Heavens (plural), would be "hemelen". But the original saying probably considered The Heavens (plural) as one thing (a collective noun like Maim (myeem) in Hebrew (The Waters). So, it could be similar to "Great Heavens!". The English "Good Heavens!" is probably the analogous saying, but a bit weaker.
Another Dutch exclamation is "drommels!" which has no equivalent in English, but would be a slightly less strong form of "Damn it all!"
The Swedish-American and Norwegian-American saying, "By Jiminy" was an oath sworn in the name of "Jesus" which is Herre Jemeny in Swedish and Norwegian, and Herr Jemine in Plattdeutsch, all of which used Jemeny to disguise the name "Jesus" to not commit the sin of using the name of "the Lord" in vain. It has been surmised that the saying was a contraction of the Latin "Jesu Domine". It could be an oath meaning, "As Jesus is Lord of Heaven and Earth......, " similar to "As God is my witness.... you will do such and such, in the form of a command (to give it credence), or to make a statement that something will come to pass, or what a person is claiming is true will be believed as such.
The saying "By Gar" is an emphatic exclamation (interjection) that can be used to emphasize or make stronger a prediction or claim in an assuring way, or an exclamation of surprise over a good, but unexpected happening. It appears to be another way of disguising using "The Lord's" name in vain, disguising an oath made in God's name ("By God!").
The American exclamation of strong surprise, "Holy Smokes", (used frequently by Batman's sidekick, Robin), is also likely to have originated as a watered down way of disguising a sinful, vain and frivolous reference to God's holyiness related to the speaker's surprise over something that's trivial when considered in relation to what is "Holy". Maybe it came originally from Eastern Orthodox or Catholic religious rites involving burning candles or incense, or swearing an oath referring to "The Lord's" use of fire and brimstone (to which the smoke is related) to punish the most sinful and wicked sinners.
As for comic books, my favourite is Carl Barks' exclamation by Uncle Scrooge McDuck for his most shocked reaction to a surprise, "Ye Cats and Little Fishes!", which he used with him only twice, as I recall, in over 2,000 pages of that character. Whereas, it seems like he used the milder form, "Ye Cats", probably over 100 times. "Great Gallopin' Galoshes!" was another I remember offhand -m also "Oh, my stars and garters!", and "Oh my Heavenly Days!"