All Tyrell Deaths – A Quick Recap Before Game of Thrones, Season 8

With course of the events that conspired in Season 7, House Tyrell is now extinct. Its seat, Highgarden, has been captured by the Lannisters, during a smart move in which they tricked Jon Snow and Daenerys to sack Casterly Rock, which was unmanned.

Margaery, Loras, Mace, and other Tyrell cousins, Season 6

After suffering a burning humiliation at the hands of the Faith, Cersei Lannister plots a revenge that’s worthy of Tywin. She begins with having Margaery and Loras arrested on charges of homosexuality for the latter, and aiding and abetting for the former. During her stay with the Faith, Margaery pretends to be reformed, due to which she is not paraded on the streets the same way Cersei was. However, the Faith does intend to hold a trial for Cersei, during which all the tyrells, and members of the Faith gather at the Sept of Baelor.

While waiting for Cersei to arrive for her trial, Margaery gets an inkling that something is wrong. She tries to convince the High Sparrow to let them all leave, but he does not relent. Cersei sets large amounts of wildfire on fire, which leads to a massive explosion in the Sept. With this, the entire Tyrell clan, apart from Oleana, are killed.
Oleana Tyrell, Season 7

Oleana Tyrell dies at the hand of Jaime Lannister, who offers her a poisoned glass of wine out of compassion. After drinking the wine, she tells Jaime about how she killed Joffrey Baratheon, and how she wants Cersei to know of the same. Jaime leaves her room in anger, and that is the last that we see of this great matriarch from House Tyrell. The golden roses have been wiped out of the realm, with Cersei still on the throne.