The instrumental theme song, titled "The Munsters's Theme", was composed by composer/arranger Jack Marshall. The theme song's lyrics, which the sitcom's co-producer Bob Mosher wrote, were never aired on CBS. Described by writer Jon Burlingame as a "Bernard-Herrmann-meets-Duane-Eddy sound", the theme was nominated for a Grammy Award in 1965.
That theme and the Lost In Space theme are my favorites.
I think both use some sort of brass instrument like a tuba or trombone for the low end (bass notes). Really 'splatty' sounding. Natural distortion.