The Colt was called the Officer's ACP. There was a Colt revolver on the medium frame called the Officer's Model. The large frame model was the Shooting Master (and there was another large frame target model, too). I owned one of the Officer's ACP. I wouldn't say it had a lot of blast but it was certainly a handful to shoot.
Star pistols from Spain were the first to produce very lightweight pistols, all single actions rather like Colt, except none had grip safeties that I recall. There was a .45 model called the PD, already mentioned, and a thin and compact model called the Starlight as well as a variety of .380 models over the years. I couldn't say how popular they were but gun writers often mentioned them.
Some PPKs were produced with an alloy frame but only in .32. I believe those were produced at least by 1960. The groundbreaking S&W Model 39 was also around by then and one company used them as a basis for a cut-down model called the ASP, I think it was. Those were also written about a lot but I never saw one.