Chris is right about the cutouts, though these full shields are a postwar development, probably by the HIAG. The designs were made by various people, as Mark indicated, the Dietrich design was originated by August Wilhelm Trabandt and his battalion of LAH during the western campaign of 1940, since they had been the "key" to force open several important defensive positions. Martin Kohlroser liked the design, and introduced it to his battalion in a separate color, and from there, it spread to the entire LAH.
Supposedly, Paul Hausser himself was sketching the matching Siegrunes as found on an SS collarpartch, and found that by making the base of one shorter, and then shortening the top of the other, he had created a design that resembled a traditional wolfsangel. This was the source of Das Reich's "kampf rune."
The symbol of the Hitlerjugend Division was designed by Rttf. Fritz Lang of the divisional staff. This is per Meyer's divisional history.
The 12-point Buck symbol of the 31. SS-Freiwlligen Grenadier Division was supposedly selected personally by commander Gustav Lombard, though I'm not sure if created the design. This is per Rudolf Pencz' research.
The famous helmet of the Nibelungen Division is a post-war creation, their wartime symbol was apparently a bird's head over SS Siegrunes.
I believe that in many units, as with Hitlerjugend, contests were held to choose the symbol, based on designs submitted my members. I recall that Vopersal's Totenkopf history included several designs considered for the title page of the IV. SS-Panzerkorps newspaper, along with the names of the designers. However, the above are the only cases I could specifically identify at this moment.