Can a judge overturn a jury decision at the end of a trial?

In America, yes. It’s very rare. A judgement notwithstanding the verdict.

Yes, they can, As @JLeslie says, it is rare. Usually it happens when the judge feels the jury has not properly weighed the evidence.

In a criminal trial, they cannot find the defendant guilty over the jury verdict. In a civil trial, they can reduce the penalty/ damages to $1.

In criminal trial, the judge may only throw out guilty verdicts. He cannot overrule a not guilty verdict and declare the defendant guilty.

Judgement notwithstanding verdict

@luigirovatti: Criminal and civil trials are different. You didn’t specify.

@jca2: That’s because I want to know all cases, of course.

You can Google it and read all about it.

Yes.