Yeah, I didn't think he was related to him either. Unfortunately there doesn't
seem to be much info on him anywhere except a few basic things. I've been trying to find more about him. Likehow tall he was, he seemed pretty tall in all I've seen him in.

My guess is that someone got confused between celebrities named MARTIN.
Kiel was married to DEAN Martin's daughter, which is where (I assume) he got his stage name he was born Kiel Mueller.
Hagman's mother was the famous MARY Martin (obviously no relation to Dean).
An understandable mistake,but one you'd assume would be caught quickly and not proliferate on the web.
Nice to have IMDB, which is pretty quick and accurate in catching these glitches.

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The info about Kiel Martin being Larry Hagmans half brother comes from findagrave.com I just came to IMDB for clarrification because I didn't believe it either.

He had no relation that I have ever seen in any of his biographies to Hagman or to Mary Martin the actress. Someone likely made a mistake in his IMDB bio.
"It's alligator, darlin'al-li-gator"

Larry Hagman's mother is Mary Martin. I guess Keil Martin's real surname likely was Mueller.