
Rembrandt?
No, Willem Drost.
Rembrandt- like most old masters- like Andy Warhol- ran an art factory. He had colleagues, pupils, assistants- some of whom established themselves as names in their own right- like Carel Fabritius; some of whom never altogether escaped his penumbra- like Willem Drost. All have suffered from having much of their work absorbed into the oeuvre of the master. There are a whole lot of "Rembrandts" out there which aren't Rembrandts at all, but the work of artists he trained. They may be in his manner, employing his line, his palette, his impasto, his models, the contents of his dressing up box, but look closely and there's something about them that doesn't ring true; they include some of the greatest works to which his name has been attached.
This for instance: the so-called Polish Rider.

If The Polish Rider is a Rembrandt then it's unlike any other Rembrandt in existence. The mood- heroical, fantastical, bordering on fairytale- isn't at all in his line. The Frick Collection, which owns it, continues to call it a Rembrandt- because that way it maintains its enormous value- but scholarly opinion now tends towards thinking it's a Drost.
Drost was born in 1633, entered Rembrandt's studio at 17, left it five years later, went to Italy, picked up commissions- and died in Venice, aged 25.
Wikipedia calls him a shadowy figure, but look at the works that have been attributed to him and a personality emerges. There's a softness to his people- a sensitivity, he liked pretty women. This Vision of Daniel is probably his.
When Rembrandt painted children they came out as chubby little brutes- and this gentle, golden haired child-angel is outside his range. Rembrandt could do tenderness- is indeed famous for it- but not quite in this style. Drost- supposing this is Drost- is less robust than his master, less earthy...
And in The Polish Rider he produced (probably) one of the greatest paintings in the world.