This is such a great movie, I'm sure that you've all seen it. For me, the real greatness of it is found in the little, incidental characters. The producer did a really thoughtful job of filling in the small spaces in Them! with classic two or three minute appearances by great supporting actors.
There's Fess Parker as a ranch manager who encounters the giant ants while piloting his plane around Texas. He crashes his plane after near misses from several "UFO's" shaped like, you guessed it, ants. In the crash, he damages a Ford on the ground. He wants to know why nobody believes him about the ants, after all, he doesn't sound crazy, does he? And besides, "it ain't like that Ford was a brand new one, it was pretty beat up to begin with, so what's the beef?"
Then there's Harry Tyler, appearing as a habitual offender residing in a hospital for alcoholics. When the officials visit him at his bedside, he notes the Army officer's uniform and wants to know if he's being drafted (he's about fifty-five years old at the time). Then he suddenly decides that he's okay with that, if his conditions are met. "If you make me a sergeant, and I can charge my booze, I'll join up!" After that, in between answering their questions, he's given to bursting out in song, "make me a sergeant, charge the booze!!!!" Harry was in 358 movies and TV shows between 1929 and 1961, so you'd know him if you saw him.
Another familiar face is Dub Taylor, appearing here as a train yard watchman who was on duty while 40 tons of sugar mysteriously disappeared. (My guess is that the ants took it.) "If I was gonna make a deal with some crooks, it sure wouldn't be over no 40 tons of sugar!" Dub gets credited with 242 appearances between 1938 and 1994.
More reasons to watch "Them!," as though more were needed.