To add to Timz's comment:
The Junkers Ju-88 has 18-cylinder Y-form engines(3 banks a 6 cylinders arranged in an Y form around the crankshaft)
While building the Tu-4(B-29 clone), the russians considered the use of their own developed, 48-cylinder X-form engines(4 12-cylinder banks arranged in an X-form around the crankshaft). However, the intention was cancelled due to unreliability and maintenance problems of these experimental engines.
The french pre-WWII Caudron racing aircraft were equipped with straight(not V) Renault 6 or 8-cylinder engines(common in cars, but not that common in aircraft, even in those years)
ALL WWII watercooled engines - the DB series(powering the Me-109), VK-105PF and VK-107PF (all Yak fighters), RR Gryphon/Merlin(Hurricane/Spitfire/Mustang), Allison(Curtiss Kittyhawk), just to mention the most popular ones were V-12's mounted inverted