Vilius Gaigalaitis or Wilhelm Gaigalat (27 September 1870 – 30 November 1945) was a Lutheran priest and Prussian Lithuanian activist.

He was a member of the Prussian House of Representatives (1903–1918), director of the consistory of the Evangelical Lutheran Church in Lithuania (1925–1933), and professor at Vytautas Magnus University (1925–1936).

Various Lithuanian schools and societies were liquidated after Lithuania lost Klaipėda Region to Nazi Germany in March 1939, destroying Gaigalaitis' life's work.

In total, Gaigalaitis published 25 books, including a study on Gemeinschaftsbewegung [de] (Community Movement) among Prussian Lithuanians and the first Lithuanian-language work on poet Kristijonas Donelaitis.

Born on 27 September 1870, Gaigalaitis was the youngest of nice children in a family of farmers in Naujienos (German: Heydebruch; present-day Naujininkai [lt] in Pagėgiai Municipality) near Vilkyškiai[1] The village was then part of East Prussia which had a large Lithuanian-speaking minority of Prussian Lithuanians.

[4] His first known article (a translation from German about Christian missionaries) was published in Keleivis supplement of Konzervatyvų draugystės laiškas in 1884 (at the age of 14).

[3] In 1886, he was tutored for nine months by priest Jonas Pipiras and successfully passed entrance examination to the Louise Gymnasium in Memel [de] (now Klaipėda).

[3] A year later, he transferred to the realgymnasium in Tilsit [de] (now Sovetsk) where, according to his memoirs, he organized a secret student group Baltija.

During this time, Gaigalaitis attended six-week courses at the teacher's seminary in Ragnit (now Neman) and taught in primary schools.

[8] In June 1900, he received doctorate of philosophy from the University of Königsberg for his thesis on the Wolfenbütteler Postil (newly discovered Lithuanian manuscript from 1573).

[5][9] Gaigalaitis chose the topic under the influence of Adalbert Bezzenberger who helped him obtain financial assistance from the German government.

He accepted a position as an assistant priest (Hilfsprediger [de]) in Eidaičiai [lt], but it was a small and remote village with no church.

In 1928, Kurt Ballerstedt published a brochure Die evangelisch-lutherische Kirche in Litauen im Kampf um ihre Freiheit (The Evangelical Lutheran Church in Lithuania in the Fight for its Freedom) with a foreword by Gustav Adolf Deissmann.

According to his memoirs, during his years at the Landtag, he delivered 14 more notable speeches, particularly on the issues of the Lithuanian language in schools and churches.

However, due to political backlash, Gaigalaitis refused to take the post and did not sign the act though he generally was supportive of the idea.

Gaigalaitis faced pressure from the German police and fled to Kaunas, the temporary capital of Lithuania, in July 1919.

[22] Gaigalaitis went on two diplomatic missions regarding the Klaipėda Region: for consultations to the United Kingdom in 1921 and as a leader of a delegation of Prussian Lithuanians to the Conference of Ambassadors in November 1922.

[4] The society maintained shelters for the disabled, Sunday schools, supported impoverished students, organized church choirs, etc.

[5] When the Spauda Society organized the Lithuanian daily Prūsų lietuvių balsas [lt] in 1919, Gaigalaitis donated 21,000 marks for the cause.

[23] Lack of Lithuanian teachers and resistance from German parents made it difficult to change the language of instruction.

[33] Povilas Jakubėnas (member of the Lithuanian Evangelical Reformed Church) was dean of the faculty, except for the 1927/1928 school year when Gaigalaitis took over the post.

[4] He taught classes on Christian missions, sociology, liturgy, ethics, exegesis, apologetics, catechesis, and pastoral theology.

[43] Starting in 1896, Gaigalaitis compiled bibliography index for journal Mitteilungen der Litauischen literarischen Gesellschaft published by the Lithuanian Literary Society.

[44] Such work culminated in a bibliographic review and history of the Lithuanian press Lietuvos nusidavimai ir mūsų rašliava published in 1912.

[43] In 1913, in preparation for the 200th birth anniversary of priest and poet Kristijonas Donelaitis, Gaigalaitis published his short biography and literary analysis of his key poem The Seasons.

This edition, published in roman and not the German blackletter, was intended for Lithuanians in Lithuania Proper and United States.

[48] Since political articles could attract police attention, Gaigalaitis published under numerous pseudonyms which makes attribution of authorship difficult.

[49] Gaigalaitis was a bibliophile and owned a rich personal library of Lithuanian publications and works about Lithuania in other languages.

[28] The library included some old and rare publications, such as Postil of Jonas Bretkūnas (1591), hymnal by Daniel Klein (1704), dictionary by Philipp Ruhig (1747).

[54] In 2022, relatives of Gaigalaitis transferred some of his personal archive to the Ieva Simonaitytė Public Library of Klaipėda County [lt].