The poster of the first starwars movie poster had a title which was streched int the back. I found out that the credits have the ITC serif gothic font, but what has the title. Is it a special thing or do I find the font somewhere?

Jay Gothic  Suggérée par conman1985 
Compacta  Suggérée par CmdrKerner 

The STAR WARS logo on this poster was likely custom. A very similar logo also appears on the 1977 paperback edition of STAR TRIAL by Irving A. Greenfield. It's possible the letterforms are based upon Jay Gothic, a 1965 typeface that was also used for the titles in the original 1966-69 STAR TREK series.

IMHO the font which comes closest is Compacta BT.