Sisinnios 24 was bishop of Gariela (location uncertain; possibly in Thrace or Thessalia); in 787 he attended the Second Council of Nikaia (the Seventh Ecumenical Council) and was probably present at the last seven sessions, from 26 September to 23 November 787 (he is not attested at the first session on 24 September): Mansi XII 1110-XIII 486. In the list of those present at the seventh session he is styled Σισιννίου ἐπισκόπου Γαριλέων: Mansi XIII 372 (the Latin version, at XIII 371, calls him: "episcopo Garilensium"). Elsewhere he is styled Σισίννιος ὁ ὁσιώτατος ἐπίσκοπος Γαριάδου (sic), Mansi XII 1110 (the Latin version, at XII 1109, has: "episcopus Garialli"); Σισίννιος ἐπίσκοπος Γαριέλων, Mansi XIII 149 (the Latin version, at XIII 150, has: "episcopus Garielensium"); and Σισίννιος ἀνάξιος ἐπίσκοπος Γαριέλης, Mansi XIII 397 (the Latin version, at XIII 398, has: "episcopus Garielensium"). He is named in a group of bishops from Thrace and Thessaly. At the second session he supported the traditional veneration of icons as described in statements from pope Hadrian I (Hadrianos 1) and condemned iconoclasts: Mansi XII 1110. At the fourth session he subscribed the statements read out from the Fathers in support of the veneration of icons: Mansi XIII 149. At the seventh session he subscribed the statement of the faith adopted by the Council: Mansi XIII 397.

(Publishable link for this person: )