(I can't find many free photos of what I want to show here. Maybe I could buy some.) See the links behind the model names for nice pictures.
Heatsinks are a mostly practical thing. They usually aren't seen, so visual design is not very important. Exceptions are where part of a device's case is acting as a heatsink and devices assembled by enthusiasts who care how their internals look (including devices that show off their components, like open PC builds and PCs with windows in their case). This post in about the latter: heatsinks for PC components for people who care how their coolers look like.
To be frank, this entry is specifically abnout Zalman heatsinks. I don't know much about the company. Apparently they are Korean with a name that sounds so un-asian that I doubt that the beginnings really were in Korea. But I know that they made several CPU coolers that I like visually. A heatsink needs to fulfil the task of transporting heat from a small surface to a larger surface where other mechanisms then may exchange heated melecules with molecules from even farther evay. Heatsinks can store more heat energy if they have a larger mass. They transport the heat quicker if they are made of materials that are good at that sort of thing, like copper. And they are better at exchanging heat with their envirement if their surface area is larger. If a chip needs to be cooled better, what's mostly done is put a larger heatsink onto it (can take in more energy) or blow more air through it (larger/faster fans). It's relatively cheap to just increase the amount of aluminium and/or plastic and call it a cooler. But making the heatsink larger mainly increases the capacity for how much heat energy it can take in from the die quickly, which is good for eneryg bursts, but not for constant heat absorbtion. And blowing more air through it makes the cooler louder. Zalman took a different applroach around 2000 and was very successful with it in the early 2000s, as it appears to me. They used mainly copper for their heatsinks (even just a copper core used to be a sign for a higher value PC heatsinks before) and they drastically increased the surface area. I don't knwo who invented the style or manufacturing principle of copper sheets intertwined with a copper base to form a fan-like (as in paper fan) structure. But Zalman did this with the most sense for beauty and with a target market of enthusiast PC builders. I couldn't afford any of their products at the time. But I was a fan from the moment I saw a Zalman Flower for the first time.
Under the name flower they released a number of very different, round CPU coolers as well as at least one chipset cooler. The name started in the 90s, where it was used for a ciurcular aluminium CPU cooler for socket 370 (Pentium III, Celeron). I like those, too. But they are impossible to find and I'm not aware of anybody making anything similar with that much metal around the fan. In my perception the copper goodness started with the CNPS 3000 series, a passive CPU cooler. Right there we have a unique design that hasn't been matched by any other manufacturer. If I would find one of these and I could buy it for < 30 €, I would get it for a future retro build. It got a makeover with the CNPS 6000 series later for socket A.
The CNPS 5000 is hardly worth mentioning. It follows the design of the Intel Standard LGA 775 coolers, but without the goal of being cheap. The CNPS 7000 series has a layout simialr to the original Flower, round with fins surrounding the fan blades from all sides except the top. Not a new design, but again, now it was available in beautiful and with a lot of copper (optionally, as it usually was from the CNMPS 5000 onwards) fins.
The CNPS 8000 has less roundness and more boringness and shall be skipped here. Now we're already in a time were CPU cooler mounts were designed similar to the way they are today and so some of these coolers are still usable with modern CPUs without making a custom bracket, for some you would need to make your own or adapt a bracket. But it's a realistic undertaking. In the CNPS 9000 series there are two beautiful models. The CNPS 9500 and the CNPS 9900.
Another unique design (as far as I've seen) is the fanless external water cooler Reserator 1, of which several version exits but all are called Reserator 1. CPU coolers aside, most of Zalman's coolers are designed for PC GPUs, understandably. There is one design that I'd like to point out here. And that's the ZM-80. Here are reviews of the ZM-80C and the ZM-80D. I bought an early version of the ZM-80 (without a fan) because it was the best way to passively cool my GPU back then. I'm not a gamer. But I still believed that I could use a powerful graphics card. And those had started to require active cooling. The two giant and massive metal plates of the ZM-80, connected with a heat pipe, made the graphics card an uncommonly large part. It was the first time that I've seen an extension card block its neighbor slot. There are similar coolers. Thermaltake < a href="https://www.techpowerup.com/review/thermaltake-schooner/">took this design to the extreme (although nowadays there are larger GPU heatsinks).
The more time advances, the more boring Zalman's product range becomes.