The closest any other crewed spacecraft comes to that longevity is the DOS space station core module (reaching its 46th crew-carrying anniversary this June), which featured in most of the Salyut space stations and the Mir space station, and is currently part of the ISS. Soyuz and DOS were designed to work together, so it's appropriate but remarkable that they're still doing so today. You'll see in the visual history below how much the two vessel types have been connected.
By coincidence, today is also the 46th anniversary of Soyuz 10's unsuccessful docking attempt with Salyut 1, the first Soyuz-DOS meetup in orbit. Later this year we'll see the 60th anniversary of the R-7 family of rockets, the oldest orbital launcher there is, variants of which have launched all crewed Soyuzes and most uncrewed Soyuzes, plus all sorts of other things.
The longest serving US spacecraft, the Space Shuttle Orbiter, lasted 30 years, and the 5 of those that were built got into space 134 times, accruing a total spaceflight time of just under 1 331 days. Flying only once each, 132 Soyuzes have gotten their crews into space 132 times so far, adding up to 14 956 days of human spaceflight time, and counting. Nine more Soyuzes are scheduled to launch, keeping them in use until 2020. Adding in all the uncrewed Soyuz and Soyuz-variant launches more than doubles the number of times the Soyuz family has flown; there were no uncrewed Space Shuttle flights. So, it's not the simplest comparison.
The second most numerous spacecraft design was the Apollo CSM, of which a mere 15 were launched into space with humans on board.
And while the latest version of Soyuz is definitely modernised and digital, it's also still clearly very close to its original 1960s form; consider below the full evolution of the Soyuz:
|(Click to embiggen.)|
Top row: Crewed variants of Soyuz.
Bottom row, left group: Major uncrewed variants of Soyuz.
Bottom row, right group: Crewed variants of Tiangong.
(Image credit mostly goes to historicspacecraft.com, with a couple bits from elsewhere and/or modified by me.)
Note that I've included more than just the crewed versions. Soyuz has been around so long, it's been mutated into a few different forms - most import of all is undeniably the Progress cargo vessel. I've also included China's larger Tiangong spacecraft, which was intentionally based on the Soyuz layout, and operates in a very similar way. It is arguably part of the Soyuz family.
One weird thing going through all of the Soyuz missions brings up is how openly sexist the Soviet and Russian space programs have been. Hundreds of people have travelled on Soyuzes, but only 3 of them were Russian women (less than 1 per decade!), and no Soyuz has ever had a woman commander. There are plenty of stories floating about of nasty sexism in Soviet/Russian spaceflight, and they even chose to put it in some of their public relations videos. One case leapt out at me from the Soyuz TMA-11 near-disaster, discussed towards the end of this post. The Roscosmos general director at the time publicly blamed the fact that the vessel concerned had too many women onboard (one American, one South Korean), and said he'd work to prevent this from happening again. You don't joke about crap like that, but I suspect he wasn't kidding.
Because Soyuz has been around for so long, it's hard to discuss absolutely every flight and every crew. At the same time, one of its virtues has been how uneventful and routine most of its operations have become. I think the best way to celebrate this 50th anniversary is a simple visual history of some of the major Soyuz moments. Even condensed this way, it's still a lot.
1966-11-26 (no image available): Kosmos 133, the first uncrewed Soyuz test vehicle, launches. It malfunctioned in orbit and was intentionally destroyed before it could crash. Two further uncrewed test launches followed, both with serious systems failures.
|1971-04-23: Soyuz 10 attempts to dock with Salyut 1, the first ever space station, but fails to completely do so. Then they had trouble getting completely loose from the station's docking equipment again, but eventually got home.|
|1974-07-03: Soyuz 14 launches, docking with the Salyut 3 space station, probably the only crewed spacecraft to be armed.|
|1975-07-17: Soyuz 19 and Apollo 18 dock in orbit, the first international spacecraft docking. They didn't do much up there, but their long-term influence has been enormous.|