Mečislovas Leonardas Paliulionis (Polish: Mieczysław Leonard Pallulon; 2 December 1834 – 15 May 1908) was a Roman Catholic bishop of the Diocese of Samogitia from 1883 until his death in 1908.

Paliulionis studied at the Varniai Priest Seminary and the Saint Petersburg Roman Catholic Theological Academy.

After graduation in 1860, he taught dogmatic theology at the Varniai Priest Seminary (which was moved to Kaunas in 1863) until his consecration as bishop of Samogitia in 1883.

[8] After the Uprising of 1863, the seminary and the seat of the Diocese of Samogitia was moved from Varniai to Kaunas so that the Tsarist police could monitor their activities more closely.

[11] According to the memoirs of Juozapas Stakauskas, Paliulionis expected to be exiled by the Tsarist authorities at any time and had a bag with necessities ready to go.

[15] He worked to improve the interior of the Church of St. Peter and St. Paul in Kaunas,[3] the new seat of the Diocese of Samogitia that was officially elevated to cathedral status in 1895.

[17] Paliulionis planned a thorough reconstruction, led by architect Florian Wyganowski [be], that would turn the church into a neo-Gothic cathedral with two 113-metre (371 ft) high towers.

However, due to lack of funding, only the neo-Gothic Chapel of the Blessed Sacrament was built (sponsored by count Jonas Przeździecki).

[19] For example, he sponsored the publication of the anonymous Lithuanian-language book Paskutinis pamoksłas wiena żemajcziu kuniga priesz smerti ("The Last Sermon of One Samogitian Priest Before Death") in 1889 (republished in 1895, 1899, and 1905).

[20] This work idealized the Polish–Lithuanian Commonwealth and considered Eastern Orthodoxy a threat, but did not question the legitimacy of the Tsarist regime, which was God's punishment for sins.

[21][22][23] However, he did not support younger priests who were more active in the Lithuanian National Revival; he assigned them to less desirable posts and kept them out of the cathedral chapter,[24][25] a notable example being Juozas Tumas-Vaižgantas.

[23] According to the memoirs of Gabrielė Petkevičaitė-Bitė, Paliulionis supported the staging of the first Lithuanian-language theater play America in the Bathhouse in Palanga in 1899 and even recruited local nobles from the Ogiński and Tyszkiewicz families to attend.

[32][33] After the ban was lifted, Paliulionis supported the Society of Saint Casimir that was established to publish Lithuanian books and periodicals, as well as the religious weekly newspaper Nedėldienio skaitymas.

[35][36] The sculptor Juozas Zikaras created bas-relief portraits of Paliulionis and his successor Gasparas Cirtautas [lt], which were installed at Kaunas Cathedral in 1927.