Who were the first people to see the risen Jesus?

Jesus appeared first to various women, who then spread the news of his resurrection to the apostles.

Jesus rose from the dead on the third day, rising in the early morning hours of Easter Sunday.

The first people to witness the resurrection of Jesus did not include Peter or any of the apostles.

Instead, it was several women who came to the tomb to anoint his body, as the Gospel of Mark narrates:

And when the sabbath was past, Mary Magdalene, and Mary the mother of James, and Salo′me, bought spices, so that they might go and anoint him…Now when he rose early on the first day of the week, he appeared first to Mary Magdalene, from whom he had cast out seven demons. She went out and told those who had been with him, as they mourned and wept. But when they heard that he was alive and had been seen by her, they would not believe it.
Mark 16:1, 9-11

The Catechism of the Catholic Churchfurther expands on this reality:

Mary Magdalene and the holy women who came to finish anointing the body of Jesus, which had been buried in haste because the Sabbath began on the evening of Good Friday, were the first to encounter the Risen One. Thus the women were the first messengers of Christ’s Resurrection for the apostles themselves.
CCC 641

Did Jesus appear to his Mother?

St. John Paul II believed that Jesus appeared to the Blessed Mother on that same Easter morning.

He spoke about it at his general audience of May 21, 1997:

Indeed, it is legitimate to think that the Mother was probably the first person to whom the risen Jesus appeared. Could not Mary’s absence from the group of women who went to the tomb at dawn (cf. Mk 16:1; Mt 28:1) indicate that she had already met Jesus? This inference would also be confirmed by the fact that the first witnesses of the Resurrection, by Jesus’ will, were the women who had remained faithful at the foot of the Cross and therefore were more steadfast in faith.
Indeed, the Risen One entrusts to one of them, Mary Magdalene, the message to be passed on to the Apostles (cf. Jn 20:17-18). Perhaps this fact too allows us to think that Jesus showed himself first to his Mother, who had been the most faithful and had kept her faith intact when put to the test.

Later on the apostles receive the news and rush to the empty tomb. They were not the first to see the risen Jesus, but later had many encounters with him before he ascended into Heaven.