1. Kupo Finale
This theme is pure beauty. With sharp edges, smooth gradients, and unobtrusive windows, this GTK theme shows that minimalist doesn't have to mean bland, and that professional can has a style all of its own.
2. Elegant Brit
With sharp contrasts and a color scheme that blends well with the background of the image, you will be able to appreciate the beauty of this theme while enjoying its out-of-the-way design.
3. VistaBut 1.2
So some individuals might complain about the merits of having a theme that makes Linux look just like Vista, but remember that an operating system is not its looks. This theme looks very similar to Windows Vista, and is quite professional.
4. Ubuntu Dust
This theme will satisfy your needs for dark colors while simultaneously presenting your desktop in a professional manner.
5. OSX Tiger
In line with the VistaBut theme, this one presents the Mac desktop for those who find it sleek and professional but want Linux as their system.
This theme looks quite nice on a KDE desktop, featuring smooth beveled buttons and a soft silver coloring.
Just because a theme is smooth and professional doesn't mean it has to look like it belongs to a 65-year-old CEO. Catartica, though its name reminds me of cataracts, is a nice splash of modern youth combined with easy-on-the-eye graphics and an a smooth look that would be appropriate for any office.
8. Murrina X-2
This theme adds the benefit of minimalism to the professional look.
This beauty is definitely a dark theme, and is as smooth as it is bold. With a dark checkered background and borders that are as simple as they are dark, this theme is an excellent option.
Candido looks like a dream, perhaps because of its excellent background or simple icons. It doesn't draw attention to itself, but instead stands proud of what it is in--a sleek, simple theme.
11. Perfect Gnome Suite
This theme is for those who like everything light in color: light background, light icons, light menus. Its background is simple and plain, while its large, almost cartoonish icons give a bold statement.
12. Wii Black
This is the perfect theme for someone who works in a slightly relaxed environment. With the menus closed, it is like any other minimalist dark theme; maximize some windows, however, and there's just enough fun going to make you smile.
13. Aero Clone
This theme is for any of you who work in a strick workplace where the slightest deviation from the norm is frowned upon. Upon a quick glance--or even a slightly longer one--this theme looks just like Windows Vista, and will keep the difference-phobes calm.
Looks pretty, no?
15. Hardy Theme
This theme is for those who like the default Ubuntu theme, but want it a little more spruced up.
16. Blue Joy
This theme is classic Linux with a professional blue background and black menus.
With a name like Moomex, who can resist? This theme is average on Gnome, but looks outstanding as KDE.
18. Black Diamond
Though this is a dark theme, it doesn't appear that way, with a bright blue background and shiny bars. A nice mix of modern feel and unobtrusive graphics.
Zukitwo is a UI that accentuates subtlety by making almost all elements flush with the rest of the environment. The overall effect is tablet like, and it works quite well.
Orta is a stunning black and white Linux desktop, but isn’t simply monochrome. The environment makes effective use of shadows and color ranges to achieve a brilliant and unique effect.
Adwaita is the default GNOME3 theme, and Aldabra uses the Pixmap and Murrine engines in creative ways to mimic and enhance that. There are still some minor issues with the implementation, but none of them deal-breakers.
22. Adwaita Cupertino
This is the default GNOME3 theme infused with Cupertino style. It has two variants built in, one inspired by Snow Leopard, and the other by Lion. Both options are superb.
Atolm is a powerful and streamlined interface that maximizes usability and productivity. It’s sharp and bold, but it always favors functional style over visual flare.
Paranoid uses a white-on-black motif to great effect. Some users might not like the default wood-grain background, but it does add much-needed contrast, and the user has the option of changing it.
25. Diehard 4
Diehard 4 is all about attention to detail. There’s a lot of structure here, and it’s an excellent option for users who like highly organized desktop environments. It’s a particularly fine choice for software and graphic designers.
Elements is a total redesign based on Elementary. All of the aspects that made Elementary so great are still here, but this has unity panel support and all the other features modern Linux users demand.
27. BSM Simple
As the name suggests, BSM Simple is light and compact. Based on the Clearlooks engine, this is a theme for users who find that most themes get in the way of their productivity.
Malys is an amazing minimalist theme that uses a light color motif. Important to know is that it’s still a work in progress, and power users will encounter some rough edges.
The developer of Absolute describes it as simple, clean and elegant, and we agree. There’s nothing innovative here, but this theme is very polished, and it does simple, clean and elegant as well as any theme.
ANewStart is a slick, clear theme that uses transparency and a number of other clever effects. This is a low-contrast theme, which we like, but may make reading and other activities difficult in some environments.
Soothe is a gorgeous and powerful theme, and its intriguing because it takes user customization to the next level. The drawback to that is that it does require the user to dig around under the hood to get the most out of it.
Hope has been around since the earliest days of GTK. This current version is refined, and it has a wide range of modern features while still managing to hold onto the basic elements that have always made Hope so popular.
Legacy is an extreme theme that has Matrix-like sensibilities with its use of colors and transparency. Legacy isn’t the right choice in all environments, but it truly is one of a kind.
This is a clean, dark alternative to Adwaita that emphasizes a gray-on-dark motif. The sharp icons and UI elements are some of the best you’ll find in any GTK theme.
35. Divergence IV
Divergence is a powerful and refined theme platform. Its best feature is the built-in configuration tool, which lets you tweak the theme down to its finest elements.
SilverImproved is the best implementation of an all-silver theme. It’s sleek and modern, and it includes two versions out of the box: light and dark silver.
Equinox is an extremely popular and heavily modified version of Aurora. It includes both a light and dark mode, and the UI elements are incredibly crisp and usable.
Zukini is a high-contrast, white-on-black theme with transparent panels. It’s simple, but extremely well done, and there are countless ways to customize it and make it your own.
Elegant is a stylish implementation of the classic GNOME desktop. It’s also one of the most user-friendly themes around, and it lets you backup and restore themes with just one click.
Sammy is third-generation Prudence theme, and it’s the default desktop for AgiliaLinux. It is very stable, has some unique features and is extremely easy to customize.
This GTK theme is a very powerful Zuki mod with a great look and many customization options. Important to know is that it’s for power users and it’s not user-friendly at all so beginners might want to stay away from this one.
BorderLine is a new GTK theme with a fresh look. We’re excited to see where this goes, but right now, it’s in the alpha development phase and a little rough around the edges.
43. Prudence Next Generation
The latest version of Prudence is sleek, powerful and customizable. There’s not a lot of innovation here — beyond the last generation Prudence that is — but it does refined and stable as well as any theme can.
Evolve is a super simple minimalist theme. This is the perfect base for users who want a lot of control to build up their own minimalist desktop environment.
45. Heavy Metal
Heavy Metal is a hardcore, heavyweight theme that has visual flair in spades. It’s a little clunky and not super productive, but it’s a good base for a gaming or home theater workstation.
Clearwaita is essentially the best features of Adwaita blended with the best features of Clearlooks. If you’re a fan of either, then this GTK theme is worth a look.
Plastiq is a superb minimalist dark theme that maximizes readability and usability, and is extremely polished and stable.
Luminaire is a refinement of “Light Theme” that overcomes some of the contrast issues inherent to that design. In the process, however, it became a little less Light Theme and a little more OSX Tiger.
49. Marples Black
Marples Black is an extremely stylish dark theme that uses numerous transparency and texture effects. There is much attention to detail here, and the developers consistently update it, so this is well on its way to becoming the best GTK dark theme available.
50. Drakfire Dream Suite
Based on Adwaita and Unico, the Drakfire Dream Suite is a powerful theme platform built color neutral, and it comes with two distinct versions built in: dark/black and light/white. It lags a little in terms of refinement, but it has a very promising future.