[5] Häyhä was born on 17 December 1905 in the Kiiskinen hamlet of the Rautjärvi municipality in the Viipuri Province of southern Finland, near the border with Russia.

[8] His father, Juho Häyhä, was the owner of the Mattila farm, while his mother, Katriina (née Vilkko), was a loving and hard-working farmer's wife.

[7] He attended school in the village of Miettilä in Kivennapa parish and helped cultivate the home farm alongside his eldest brother.

[9] Not keen to hog the spotlight, he usually stood at the back in group photos during his youth, until his later successes forced him to take centre stage.

[11] Häyhä served as a sniper in the Finnish Army during the 1939–40 Winter War between Finland and the Soviet Union, under Lieutenant Aarne Juutilainen in the 6th Company of Infantry Regiment 34 (Jalkaväkirykmentti 34, or JR 34) during the Battle of Kollaa in temperatures between −40 and −20 °C (−40 and −4 °F).

[5][6] Finnish historian Risto Marjomaa questions the large number, as confirmation of casualties was difficult due to the absence of the bodies.

In his article, published by the National Biography of Finland, Marjomaa credited Häyhä with the total number of "more than two hundred" kills.

[25] On 6 March 1940, just a week before the end of the war, Häyhä was severely wounded when an explosive bullet fired by a Red Army soldier tore through his face and shattered his lower left jaw.

[10] Recovery took considerable time and required extensive treatment and multiple surgeries, leaving visible scars that remained for the rest of his life.

[1] As an additional honour, on 17 February 1940, he received a nameplated SAKO M/28-30 “Pystykorva” Honorary Rifle (serial number 100 781), donated by Eugen Johansson, a Swedish businessman and supporter of Finland.

However, due to administrative reasons, the knighthood was not granted, as the cross was not awarded to anyone solely for achievements in the Winter War.

The museum, opened in 1983, covers the Battle of Kollaa, and features a special permanent exhibition dedicated to the life of Simo Häyhä.

Häyhä's family farm was located in the territory ceded in the peace agreement, forcing him to start his life over in Valkjärvi ("Whitelake"), Ruokolahti, a small municipality in southeastern Finland, near the Russian border, where he worked as a farmer.

[25] Häyhä also served as a long-time board member of the Kollaa Fighters' Brotherhood, formed after the Winter War in May 1940.

[10][28] The injuries he sustained in the war left recognizable facial scars, so as a well-known person, he avoided large groups of people.

[34] In an Independence Day interview with Helsingin Sanomat in December 2001, shortly before his 96th birthday, Häyhä opened up about his war experiences.

"[7][35] Häyhä spent his last years in a war veterans' nursing home in Hamina, where he died on 1 April 2002, aged 96.

Swedish heavy metal band Sabaton composed the song "White Death" in honor of Häyhä, which was released in 2010 on their album Coat of Arms.

[37] Scottish black/thrash metal band Achren's three-song The White Death EP from 2014 is dedicated entirely to Häyhä, right down to the cover art.

[37][38][39] Japanese metal band To Mega Therion has made a song called "Simo Hayha", which appears on the 2015 Yog = Sothoth album.

[44] American author Arna Bontemps Hemenway has written a short story about Häyhä, called "Wolves of Karelia", which was published in the August 2019 issue of The Atlantic magazine.

[37][49] He also appears in the manga Record of Ragnarok (Japanese: 終末のワルキューレ, Shūmatsu no Warukyūre) by Shinya Umemura and Takumi Fukui, in which he is depicted as a fighter for humanity.