The Singleton Flash Logo
You can take a fun tour right over here of the various Flash Comics logos that have been employed by DC Comics since Flash Comics #1 hit the racks back in 1940. But one logo is missing from that display.
Up above you can see the cover of Flash #18 from 1988. The 1980s version of the Flash logo would have obscured too much of the gravestone statue that cover artist Andy Kubert had drawn, so editor Barbara Kesel made the right call and ordered up a one-use-only logo for The Flash. Sleek yet bold is how I might describe it.
I would not mind seeing that logo used again one day.