I do kind of like it when Batman says "don't get involved, I'll handle it" then immediately gets strangled.

Checking Mike's, this issue came out the same week as the Demon #13; and I'm wondering if this maybe wasn't the first non-Kirby Demon? From 1973, the Brave and the Bold #109, "Gotham Bay, Be My Grave!" Written by Bob Haney, art by Jim Aparo.

Batman gets called in, after a monster emerges from said Gotham Bay; while in an upscale portion of the city Glenda Mark is this close to putting something together: namely, that all these old portraits Jason Blood had of his "ancestors" look like him! Jason laughs it off, because this was back in the day when the hero's secret identity was sacred, not just because he's being a jerk. But, his friend Harry is on his way to his boat, when he too is attacked by the monster. (If you keep reading Demon comics, that's nowhere near the worst thing to happen to Harry!) Before Jason gets involved, there's a full page of him talking with Merlin, who was maybe like his boss at this point? Still, Etrigan saves Harry, but gets slapped around a bit. Then while giving chase, Etrigan is netted by Batman! Harry and Randu arrive in time for Randu to change him back to Jason, letting him in on the secret he wouldn't tell Glenda! (It helps that Batman recognizes them all: Jason was a "prominent demonologist," Harry "Gotham's top huckster," since he was an ad man, and Randu a "famed U.N. delegate.")

After Harry's attack, Batman has realized the monster was attacking sailors or seafarers; while Randu has to do most of the legwork via ESP: he sees a ship near Krakatoa in 1883, that was going to hang sailor Jack Dobbs for murdering the first mate. Instead, the volcanic eruption destroys the ship with all hands, but Jack somehow lives on. Batman warns Jason off the case, then tries to lure out the creature, but he may have bit off more than he could chew: the tranq he had prepared doesn't break the creature's skin! Getting choked out, Batman has to admit, maybe he did need the Demon there...

Of course, Jason doesn't quit that easy: changing to Etrigan, he breaks into the Gotham Museum to get...a coil of rope? Meanwhile, the creature that had been Jack Dobbs brings Batman out to the raised wreck of his ship like Bats was Julie Adams in Creature from the Black Lagoon; then jumps the Demon when he arrives. The fight isn't going terrible, until Merlin, steamed that Blood missed their appointment, takes away his power, turning Etrigan back into Jason! Randu ESP's Merlin, who realizes his error and restores Etrigan. The Demon then tears the metal collar off Dobbs--his defense against being hung--and strings him up with the rope, which had been from the original boat...I don't think hemp holds up like that, even if it had been in a locker? Would a 90-year old rope hold him...oh, it's probably magic, sure. With Dobbs dead, again; the boat sinks again; and the closing captions seem to hype up the Demon returning to B & B someday--and Etrigan would, in #137. Huh, that was it? I was expecting to see like a third team-up in there.