Both were superhero spoofs that turned out to be half-season wonders.
https://en.m.wikipedia.org/wiki/Captain_Nice
https://en.m.wikipedia.org/wiki/Mr._Terrific_(TV_series)

While William Daniels of “Captain Nice” eventually found greater fame in Hollywood, Steven Strimpell of “Mr. Terrific” did not. A few years before his 2006 death, he gave an interview to “Outre” (either a print or online magazine) talking about his negative experiences with the series.
https://www.imdb.com/name/nm0834519/bio?ref_=nm_ov_bio_sm

I generally like 1960's TV shows but neither of these were very good, both lasting for only a half season and deservedly so.

I generally like 1960's TV shows but neither of these were very good, both lasting for only a half season and deservedly so.

They were trying to cash in on the “Batman” craze.

They were trying to cash in on the “Batman” craze.

This is true. CBS and NBC tried for a ratings grabber of their own in response to Batman, but neither show was a particularly inspired effort and both were half season failures.

As it turned out, Batman didn't really have long term staying power either as it's time on the air, 1966-68, was fairly short. Batman was a fad that rose quickly and shone brightly for a time, then the shine began to fade and eventually disappear.

I read somewhere once that MR. TERRIFIC is never shown anywhere because of implied drug use; or something.
I remember years ago in 2001 or 2002 TV Land showed 2 episodes of it though.

I do, and I remember how Captain Nice got his name. It was from the initials on his belt buckle, which were CN for his real name Carter Nash.

I remember these shows well. I remember as a kid you either liked one show or the other, not both. I was on the side that liked Mr. Terrific better. We as kids would argue who's the best and who'd you'd rather be. I remember Capt. Nice, but I think I only watched one or 2 episodes, but Mr. Terrific I thought was great and was so disappointed when it was taken off. I felt like Ricky Ricardo, "Wha happened?" John Mcgiver as Mr. Terrific's boss was really funny and the guy who was Mr. Terrific's pal and co-worker at the gas station I believe was later Hymie the robot on Get Smart (though I never liked Get Smart). I wish they'd release the Mr. Terrific series on DVD, I'd buy in a minute. I did get episodes of this series in a trade some years ago. I can still sing the theme song, at least the first 2 words, "Mr. Terrific dee dee dah dee dah dah" It was catchy.

I recall that Carter's father, Mr. Nash, in contrast to the constantly fidgety and meddlesome Mrs. Nash, not only never said a word but ALWAYS was seen behind a newspaper doing his best to stay out of everyone else's way! One wondered if he may have dropped the paper after his marriage only long enough to conceive Carter way back when then.

I remember Mr.Terrific but not Captain Nice.

I remember them both. I was 11 and loved both of them and was mad when they were cancelled.
I remember once I was talking about Mr. Terrific with a friend who I thought also liked it and he said "MR. TERRIFIC? THAT SHOW STINKS!!"