The first few decades of Christianity were replete with Jewish converts who went on to become saints or martyrs for the Church. (I think most or all of the twelve apostles were Jewish, for example.) However, I don’t recall any later cases of a Jew converting and subsequently being canonized by the Roman Catholic Church. Have there been any Jewish saints since the Middle Ages? In fact, who was the most recent Jew to have converted to Catholicism and been formally canonized?
Edith Stein (1891-1942), a victim of the Holocaust, was canonized by Pope John Paul II in 1998.
Orthodox, not Catholic, and they’re not officially saints yet, but canonization in the Orthodox Church happens from the bottom up, not from the top down as in Catholicism, and so saints are venerated locally before they are officially canonized.
The late Protopresbyter Alexander Schmemann was of Jewish origin, and is an extremely prominent modern Orthodox theologian; there’s a strong movement to have him canonized, and it seems likely it will happen eventually.
Another modern Orthodox priest, Fr. Alexander Men, was Jewish, but was baptized as a child when his mother converted to Orthodoxy. He was murdered 15 years ago by a Russian neo-fascist, likely because of his Jewish background, and is another strong candidate for future canonization.