It’s a strange sort of legacy, but it’s the kind that’s ever present – the dreaded spinning pinwheel or beach ball or wheel of death. That bright, rainbow colored circle that pops up when an application in busy in macOS.

It’s one of the most instantly recognizable of Keith Ohlfs’ many contributions to the modern operating system interface. The UX designer, who passed away last week at age 52, played a key role in designing NeXTSTEP, the UNIX-based operating system used for NeXT Computers – the computer company Steve Jobs launched after his untimely exit from Apple in the mid-80s.

While NeXT was never destined to become the computing powerhouse of its predecessor, the company would lay the groundwork for the feature of Apple after its acquisition in 1997. And Ohlfs’ work would be an important piece of that future, as NeXTSTEP became the foundation of OS X/macOS.

An article in NeXTWORLD Magazine’s Summer 1992 issue highlights his work at the time,

As resident artist, he’s drawn practically all of the icons that NeXT uses. He’s also responsible for a large part of the computer’s distinctive look, from NeXTstep’s three-dimensional controls to the anti-aliased icons that seem to have more resolution than the screen should permit.

Since then, Ohlfs has worked on a number of high profile projects, including UI design for WebTV and Vudu. Most recently, he was employed at HTML5 application designer Montage Studio. A donation fund for his family has been set up in his name on GiveForward.