Jesse Eisenberg famously played Lex Luthor in Batman v Superman: Dawn of Justice and Justice League. His character was responsible for the deaths of multiple people, all just to tear Superman down. He went as far as to kidnap the Man of Steel's mom and seemingly torture her, before Batman ultimately came to the rescue.
Given that, it's safe to say Eisenberg's Luthor has been one of the most ruthless depictions of the villain so far. Fortunately, the actor couldn't be further from his character in real life, as he is actively working to save someone's life by donating his kidney to them. 
Promoting his upcoming film, Now You See Me: Now You Don't, Jesse Eisenberg went on the Today show. During the interview, the actor's proclivity for blood donation came up, leading him to reveal he will be donating his kidney in December as an altruistic donor: 
"I'm actually donating my kidney in six weeks. I really am. [...] I don't know why, I got, like, bitten by the blood-donation bug. [...] I'm doing an altruistic donation, mid-December, yeah."
For those unaware, an altruistic donor—also known as an altruistic living donor, or non-directed kidney donor—is an individual who donates their kidney to someone they don't know personally.  As Eisenberg explained in another interview with Today.com:
"Let's say person X needs a kidney in Kansas City, [and] their child or whoever was going to donate to them is, for whatever set of reasons, not a match, but somehow I am. That person can still get my kidney and hopefully that child of that person still donates their kidney, right? But it goes to a bank where that person can find a match recipient. But it only works if there is basically an altruistic donor."
Eisenberg also revealed he had intended to become a donor for 10 years, and even reached out to an organization to make it happen. Though he didn't hear back from them, he was able to fulfill his goal when a friend of his who's a doctor referred him to the NYU Langone Health hospital. With so little donors available, organ transplants are a significant challenge for many. As reported by the Health Resources & Services Administration, in the United States alone, there are currently over 103,000 women, men and children on the national transplant waiting list. 
Thus, it cannot be overstated how big of an action this is on Eisenberg's part. Donating such an important part of yourself for the benefit of a person you don't know is perhaps one of the greatest acts of kindness someone can carry out. Furthermore, having a person of his caliber and status publicly discussing organ donation on television may encourage those in a position to donate to do so as well. As he told Today: "It's essentially risk-free and so needed. I think people will realize that it's a no-brainer, if you have the time and the inclination."
It's an act of kindness that will hopefully spread out, little by little, until as many people as possible receive the care and help they need. 
Jesse Eisenberg can next be see in Now You See Me: Now You Don't, hitting theaters November 14, 2025.