Trivia: In the show, Klink is depicted as thoroughly unmusical and an atrocious violinist. In real life, Werner Klemperer was a proficient violinist and also a piano player. After the show was canceled, he worked as a classical musician.
Reverend Kommandant Klink - S2-E25
Trivia: In this episode, Major Wolfgang Hochstetter makes his appearance. He is portrayed by Howard Caine, who played two other characters before this, one as a anti-aircraft battery commander, and another as a special investigator for the SS.
Trivia: Hans Speer, the factory owner, was played by Hal Smith, who fans of old television shows would know better as Otis, the lovable town drunk from Mayberry, on the Andy Griffith Show.
Everybody Loves a Snowman - S3-E14
Trivia: For budgetary reasons, it was not unusual to see one actor play several different characters in a television series. Case in point, in this episode, Noam Pitlik plays the part of an escaped POW. In the pilot episode, he was a Gestapo agent, and various German officers in others.
The Great Impersonation - S1-E21
Trivia: Toward the end of the episode, look carefully at the Commandant's office exterior of Stalag Four. It has a white railing, a few other support pieces, and a sign "Stalag 4" under the office sign. It is the same exterior for Klink's office, just re-dressed.
Trivia: Werner Klemperer was Jewish. When he was a child, he and his parents fled Germany when WWII broke out. Klemperer plays Klink as a buffoon, always losing in the end, and totally oblivious to the Allies shenanigans; he insisted that it be written into the contract that this formula be followed. Otherwise, another man would have been Klink.
Never Play Cards with Strangers - S4-E7
Trivia: On the wall that is adjacent to the door to Klink's office, there is usually a picture of "Old Bubble Head" (as Hogan calls him in this episode) talking at a podium; that is usually where the bug is located for Klink's office. This time, however, there is a picture of Hitler standing with a group of people, possibly a parade review.
Trivia: Hogan's Heroes was originally conceived as a comedy set in a U.S. Penitentiary. Creator Bernard Fein tried for four years to sell it, gave up, and was headed home on a plane when he saw a passenger reading the novel Von Ryan's Express. That gave him an idea. He flew back to Hollywood with a proposal for a show now set in a German P.O.W. Camp, and sold the series in four days.
Trivia: When the outside night time activities were filmed (i.e., entering or exiting the Emergency entrance, et cetera), and it was at the back lot film location, it was during the day, and the cameras were fitted with "night lenses." This was a special filter that turned day time to an evening setting.
Answer: Nimrod's actual identity was never revealed in the series. It was only known that he was a British intelligence agent. Nimrod was not Colonel Klink. Hogan had only implied it was him as a ruse to get Klink returned as camp commandant, not wanting him replaced by someone more competent who would impede the Heroes war activities. The term "nimrod" is also slang for a nerdy, doofus type of person, though it's unclear why that was his code name.
raywest ★
"Nimrod" is originally a king and hero mentioned in the Tanach and taken into the Bible and the Koran. His name is often used in the sense of "stalker," "hunter," and sometimes figuratively as "womanizer" as in "hunter of women." I've never seen it used to denote a nerdy person, and although I cannot disprove that connotation, I think given his role, the traditional meaning is more likely the intended one.
Doc ★
It's widespread enough that Wikipedia has an entire section on it: https://en.wikipedia.org/wiki/Nimrod#In_popular_culture