The Laskaris Dynasty (1204-1261)

The Laskaris Dynasty ruled the Byzantine Empire in exile being the Empire of Nicaea throughout its entire existence (1204-1261) as Constantinople was under the rule of the Latin Empire since the 4th Crusade's capture of it in 1204. The Laskaris Dynasty had 4 emperors in total being:
Theodore I Laskaris (r. 1205-1221)
John III Doukas Vatatzes (r. 1222-1254), his son-in-law
Theodore II Laskaris (r. 1254-1258), his son
John IV Laskaris (r. 1258-1261), his son
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It ended in 1261 when the boy emperor John IV was blinded, dethroned, and imprisoned by Michael Palaiologos who restored the Byzantine Empire by recapturing Constantinople from the Latins and thus crowning himself as emperor. On the other hand, it is also speculated that before Theodore I established the Empire of Nicaea in 1205 with himself as emperor, his brother Constantine was already an unofficial emperor for a year (1204-1205) following the fall of Constantinople to the 4th Crusade, although after 1205 Constantine had disappeared from historical records. The Laskaris Dynasty too was related to the Bulgarian Asen Dynasty while a branch of it later ended up in Italy and the Iberian Peninsula.