I knew 2 at least. They could run literal circles around whole experienced team and achieved sometimes, ie if given ie a week things that would be hard for seniors to do at all.

I talk about ie taking ActiveMQ, building it on your own and tweaking various calls and internal parameters to achieve cca 10x performance boost compared to just vanilla installation. Companies bundling it as part of the product would kill and pay serious money for such distro. Guy did this in maybe 3-4 days from never touching ActiveMQ or any other similar messaging system before to have it reliably working and moving to next thing.

These folks can be dangerous though, they come up with complex solution that can be extremely hard to maintain, debug and evolve by others. So their added value on long enough time scale can be actually negative even for quite senior but not absolutely top notch brilliant team. Not something 'code ninjas' (or as I call them brilliant juniors) care about, but if you work on something long term you will see this pattern from time to time.

Also these folks are hard to keep since they get bored when things slow down and big challenges are not around, and quickly and easily move on. Making the issue above pretty serious item to consider.