Valentinian III. AV Solidus. 4.42 g. Struck AD 437-438.       Thessalonica mint. 

D N PLA VALENTI-NIANVS P F AVG, diademed and helmeted, draped and cuirassed bust right.
FELICITER NVBTIIS, wedding scene with Theodosius II standing facing in centre, his hands of the shoulders of Valentinian III and his daughter Licinia Eudoxia; all three nimbate-crowned and wearing ornate marriage robes.

Mintmark COMOB. 

RIC X -; DOCLR -; Depeyrot -. 
Apparently unpublished.

Added: this coin from Tkalec AG was the first example discovered. 

Commemorating the marriage of Valentinian III to Licinia Eudoxia on 29 October 437. The couple spent the winter of 437-438 in Thessalonica, at which time this coin was struck.

With permission of Tkalec AG, auktion 29 February 2000, lot 452. 
Resold by Tkalec AG in their auction on 19 Feb 2001 with an opening bid of 30,000 Swiss Francs. 
It was later offered at the CNG Triton VII Sale, 12 Jan 2004, lot 1061 and then by Numismatica Ars Classica, auction 100, Lot 724, May 2017.