Isaac II (restored) and Alexius IV Angelus (1203-1204).

Tetarteron. Constantinople, 1203. Half-length figure of the Theotokos orans, nimbate, wearing maphorium over chiton, nimbate head of Christ on breast; in field l. and r., MP and ?. Rv. [IC]AAKIOC DECPOT. Isaac standing facing, wearing stemma, divitision, jeweled loros and sagion, holding labarum and globus cruciger. Æ 4.91 grams, 6h. DOC 1a.1 (same dies); 
Sear 2019. Very rare, of considerable historical interest. Good Very Fine. (650-700)

Isaac II was restored as a puppet ruler by the forces of the Fourth Crusade. His rare coinage, during his brief reign with his son Alexius IV, were the final issues of this mint prior to the capture and sack of the city by the crusaders on 12 April 1204. 

Ex Numismatic Fine Arts sale, October 1988, lot 1110.

With kind permission of Stack's Ltd, Auction of The Golden Horn 
Collection, Jan. 2009. Lot 3299, sold for $2600.