Narrowing the options down to basically two: the Creature from the novel, and the most commonly thought-of iteration, the Universal model.
In the novel, the Creature is fully eight feet in height and presumably proportionate with his height, making him much stronger than normal just in terms of mass. However, he’s also depicted as superhumanly fast and agile, as well as “impassive” (his own words) to exposure to the subzero Arctic. He is, however, susceptible to injury and comes close to perishing from a gunshot wound to the shoulder.
In the Universal films, the Monster starts off in 1931’s Frankenstein as either considerably stronger than normal or possessed of immense strength when enraged, since Dr. Waldman warns Henry that his furious Monster will bash his way though a heavy dungeon door within a matter of minutes. That’s only a suggestion of his strength; the only real depiction in that film is the Monster’s ability to strangle Waldman to death in under 10 seconds just as the old doc is about to dissect him, as well as his ability to quickly hang the hunchback Fritz with his own whip from the rafters. The Monster is also noted in Waldman’s journal as showing rapidly increasing resistance to ever heavier sedation. So based on those facts alone, the original Monster is already extremely if not superhumanly strong, at least when agitated.
In Bride of Frankenstein (1935), the Monster has survived the windmill inferno but has been noticeably fire damaged. His strength is still considerable: the most notable feat in this film is his busting the chains the cops have confined him with, then busting down the jailhouse door (and taking a couple bullets in the process, which only seem to annoy him). He is buried inside the mysteriously exploding watchtower at the very end but, of course, survives.
In Son of Frankenstein (1939), the Monster trashes the lab but it’s nothing spectacular. He opens a heavy stone door one-handed, the same door which Igor has much trouble opening. His biggest feat in this film (as revealed in Ghost of Frankenstein) going dormant and surviving a fall into a 800° boiling sulfur pit.
From here on, the Universal series begins losing steam and continuity (such as it already was) suffers.
In Ghost of Frankenstein, the Monster (Lon Chaney, Jr.) is recharged by a lightning bolt to the neck, an impressive scene even now. He busts some chains and crushes his old pal Igor behind a lab door…and that’s about all I can recall from that one.
Next was Frankenstein Meets the Wolf Man, which purported to showcase the Monster at full recharged power, tossing heavy lab equipment around like cardboard and smacking the Wolf Man around whenever he managed to get ahold of him. It’s kind of ironic that the Monster gets to do so much fun stuff (if briefly) since Bela Lugosi was forced to take this role and makes for a most unimpressive Monster.
Then comes either House of Frankenstein or House of Dracula (I forget which)…the Monster (Glenn Strange) doesn’t get to do much in these films as best I recall, but is saved for the final reel where he busts off the lab table and kills some folks.
Finally, for Universal anyway, was *Abbott and Costello Meet Frankenstein *(1948). In what could have been an utter travesty of a clownshow lampoon of the classic old monsters, Universal let them go out with grace and style. In this one, the Monster (Glenn Strange at his most visually impressive as the Monster) is at first very weak to the point of near-coma. Yet even in this state, he manages to bust apart a heavy nailed shipping crate from the inside, then carry Count Dracula’s couple hundred pound coffin full of dirt with one hand and no visible strain…and this is when he’s very weak. At the end of the film, fully recharged, the Monster goes on a deliberately hilarious rampage after Bud and Lou. While he chases them toward a boat dock, the boys lock a tall iron gate behind them as the surprisingly quick Monster approaches. Reaching the gate, the giant busts the lock and rips one of the gates out of its hinges with one hand. Minutes later he’s consumed in a blaze of gasoline on the dock, breaks through it and falls into the water beneath.
From then on, the only feats of strength or endurance performed by any Frankenstein that stand out in my mind:
**Evil of Frankenstein *(1964). This Hammer version of the Monster survives a rifle shot to the head and subsequent freezing for years in a glacier. Strength-wise he doesn’t do much except break a cop’s neck, beat another guy to death by slamming him against a wall, and rip open a flock of sheep with his bare hands. And he’s a really mean drunk.
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Frankenstein: The True Story (1973). TV movie with Michael Sarrazine as the slowly degenerating “perfect” Creature. Lots of feats in this one: breaks wooden arms of a chair without noticing; suicidally stabs himself in the heart to no avail; walks away from a running leap off the cliffs of Dover; survives a massive chemical explosion; pulls off Ms. Creature’s head at after crashing her coming out party; takes point-blank shotgun and pistol shots to the gut without notice, and survives the Arctic with no sign of discomfort.
*Frankenstein Unbound (early '90s, I think). Smacks some guy’s head clean off.
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Frankenstein’s Monster Talks!, from the 1960s-1970s vinyl album *Famous Monsters Speak! *(flipside is Dracula’s Return). The Monster on the album cover is depicted *a la *Glenn Strange’s Universal Frankenstein but is extremely intelligent, philosophical and verbose, yet a brutally genocidal psychopath. In this drama voiced by Gabe Dell, you hear the Monster murder an entire family, accidentally murder a chick he tries to put the moves on, and bust into a carriage to literally rip apart the guy inside – you hear him literally *rip *the dude to pieces, after which the Monster muses, “They come apart so easily! So easily…” A bit hammy in several spots but truly creepy to listen to with the lights out and a storm approaching, this album was marketed for kids but I seriously doubt it would be released for kids today, assuming it were made today.
That’s all that comes to mind so I guess the answer is, as stated above, it depends on which version of the Monster you’re talking about.