superstar

noun

1. Someone who has accumulated a vast amount of fame; a high-level celebrity.

   “Near-synonym: all-star (sometimes synonymous)”

2. An exceptionally productive employee.

   “Near-synonym: all-star (sometimes synonymous)”

   “Want to hire a coding superstar? Call the agent.”

   “Is your organization looking for its next new hire, that superstar performer to take things to the next level? Be careful: Organizations are greater than just one individual. If you're that superstar, remember to be a good team player. You'll feel better about your job and you'll perform at an even higher level.”

   “"A superstar employee that is creating that toxic work environment is probably costing that company more than he or she is bringing in," Martin says.”

   “There's no sense in hiring a superstar developer who will quit after three months because she can't stand the management style or requires flexibility the hiring company doesn't offer.”

3. (rare)A giant star; (loosely) any giant star, bright giant, supergiant, or hypergiant.

   “The greater an object's mass, the greater its gravitational force. If a star could attain a certain mass --- say a million to 100 million times the mass of our own sun --- then its gravity would become 100 times as powerful as the forces generated by the strongest known nuclear reactions. Such a super superstar, in a normal course of its evolution, would contract.”

   “Toward the centre of the cluster, where they were more strongly congested, the whole region glowed as though as it were a monstrous superstar.”

   “Perhaps a supermassive cluster can coalesce to form a superstar -- a star with a mass of 1 million to 100 million solar masses.”