Captain Nice was created by Buck Henry, who helped create Get Smart and would later help launch a little show called Saturday Night Live. It is seldom seen in the U.S., but still has a substantial cult following. It's an out and out slapstick involving the exploits of Carter Nash, a mild-mannered police chemist in Big Town, U.S.A., who discovers Super Juice, a glowing liquid that transforms him into a crime fighter for exactly one hour per day.
Unfortunately, Captain Nice was no stronger a personality than Carter was normally - shy, quiet, unassuming, and totally dominated by his mother. In fact, it was his mother that sewed him a really stupid costume and demanded that he wage war on the evil forces that constantly threatened Big Town. If it weren't for his mother's constant nagging, Carter Nash would never have gotten actively involved in any type of crime fighting.
William Daniels played the Captain, chosen possibly because of his unassuming appearance. A steady actor, he would later gain fame again as Dr. Craig on the long-running St. Elsewhere, but his voice would be heard by millions more viewers as that of K.I.T.T., the futuristic automobile on Knight Rider.
Now on to the pill popping Mr. Terrific. This was actually the worse of the two shows. It was almost as if CBS had read a plot synopsis of Captain Nice and quickly created a hack version.
Mr. Terrific was set in Washington D.C. where Stanley Beamish, a nice, shy, soft-spoken, gas station operator accidentally got involved with the Bureau of Secret Projects. The BSP had developed a secret power pill that only worked on Stanley, turning him from weakling to superhero. The gimmick of the power pill was that it only worked for one hour, once a day. Each week had Stanley doing things like, investigating enemy agents and struggling to adjust to his new secret identity and of course to all of the problems he faced when he turned back to normal at the most inopportune times.
Even though both of these Batman wannabes are nearly clones of one another, Captain Nice is actually kind of watchable, in a painful sort of way.
Batman was known for its A-List guest stars playing villains each week. Mr. Terrific never had a single celebrity guest star for its entire run; on NBC, Captain Nice had Vic Tayback, Joe Flynn, Pat Harrington, Victor French, and Bob Newhart as guest badguys.
On a side note, Mr. Terrific is banned from syndication because every episode revolves around taking pills to become a superhero, a subject that has since been deemed harmful to child viewers. For the same type of reasons, Captain Nice is no longer available in the United States, but it is still in syndicated distribution in most other countries (should they ever decide they want to watch it).
Incidentally, ABC 'borrowed' a great deal from both of these duds to create The Greatest American Hero almost a decade later.