Tzadikim

Served as the fourth Nassi [president] (in the fourth generation after Hillel) from the family of Hillel. He was the Nassi of Sanhedrin in the generation of the destruction of the second Holy Temple. R' Shimon was the first of the Ten Martys killed.

Very few of the teachings of Raban Gamliel have been recorded in his name; many have been recorded in the name of the school of Hillel.
He said: "All my days I have been raised among the sages and I have found nothing better for the body than silence; not study but practice is the chief thing; he who is profuse of words causes sin (Misnah Avot 1:17).

During the celebrations of Simchat Beit HaShoava ("Festival of the Water Drawing") on the holiday of Sukkot, R' Shimon Ben Gamliel "would juggle eight burning torches and not one of them fell to the ground, and when he prostrated himself he placed his finger on the ground, bowed, kissed the ground, and immediately stood upright' (Tosefta Sukkot 4:4 ; Sukkot 53a).

When there was a large increase in the price for certain birds that were used as sacrifices for women after childbirth, R' Shimon Ben Gamliel swore that he would not go to sleep that night until the price was reduced (Misnah Keritot 1:7).

R' Shimon had two sons and one daughter by the name of Imma-Shalom who married Rabbi Eliezer Ben Horkenus (R' Akiva's teacher) (Bava Metzia 59)

The Ten Martyrs
  Lupinus the Roman Emperor at the time was studying Torah and asked the ten great sages of that time: "What is the law according to your Torah, for a Jew who sells another into captivity?" (referring to the sale of Joseph by his brothers) "Capital Punishment," answered Rabbi Akiva and his colleagues. "But, Yosef's brothers were never punished for their crime!" the Roman protested, and then began to set his deadly trap. "Justice must be done, and there has been no leaders to take their places until the ten of you!".
  When R' Nechunya ben HaKana heard of this decree, he told R' Yishmael Ben Elisha to asend to Heaven to ascertain whether this was the result of heavenly decree. R' Yishmael purified himself, uttered God's secret name, and ascended to Heaven. He asked the angel Gavriel about the decree, and Gavriel responded, "Accept it upon yourselves, righteous and beloved men, for I have heard behind the partition that this is to be your destiny," and R' Yishmael was told that the ten sages would be given to the evil angel Samael as a punishment for the selling of Yoseph. R' Yishmael reported to his colleagues what he had been told, and they accepted the heavenly decree.
  R' Yishmael and Raban Shimon ben Gamliel were imprisoned together, and R' Shimon began to weep. R' Yishmael said to him, "Soon you will be among the saints in the next world. Why are you crying?" R' Shimon answered, "I am not crying because I am going to die, but because I am being executed like a Shabbat desecrator or an idol worshiper or ...a murderer." R' Yishmael suggested that maybe while he was eating or napping a women came to ask if she was considered a niddah and his attendants did not allow her to come in and disturb him...or a beggar may have knocked on the door while R' Shimon
was eating and his was not allowed in...R' Shimon asserted that he was extremely careful in these matters. R' Yishmael suggested that maybe he felt pride while he was teaching...and R' Shimon once again asserted that he was
careful not to have proud thoughts after he preached. (Some reverse the roles and say that R' Yishamel was crying and R' Shimon said these things to him).
  When R' Shimon and R' Yishmael were taken out to be killed, R' Yishmael fell at the feet of the executioner and begged, "I am a Kohen Gadol, the son of Kohanim Gedolim; kill me first so that I will not see the death of my fellow." R' Shimon pleaded, "I am a Nassi, the son of a Nassi; kill me first so that I will not see the death of my fellow." The executioner cast lots, and the lot fell on R' Shimon to be killed first. The executioner immediately decapitated R' Shimon. R' Yishmael hugged the head to himself and placed his eyes against the eyes of R' Shimon and his mouth against R' Shimon's mouth.
In a loud voice he cried out, "You holy lips; you never spoke anything but secrets of the Torah. How can you be made to lick the dust?"

     When Rabbi Akiva and Rabbi Yehudah ben Bava (or Betairah) heard about the deaths of Rabbi Shimon and R' Yishmael, they arose, put on a sackcloth, tore their garments in mourning, and said, "If there was any good in the world, it was
in the merit of R' Shimon & R' Yishmael. Great misfortunes will befall the world"
  Their deaths had been previously prophesied by Shmuel HaKatan, who predicted before he died (before the Temple was destroyed), "Shimon and Yishmael will die by the sword, and their colleagues are destined to be murdered..."(Sota  48)

  According to the Ari (R' Yitzchak Luria),  R' Shimon was the reincarnation of one of the brothers of Yosef HaTzaddik (Joseph) who sold him. R' Shimon's death was an atonement for that sin.

May the merit of the Tana Raban Shimon Ben Gamliel, protect us all, Amen