I very much enjoyed his understated performance in the movie Just a Gigolo. Gosh, that was made in 1978. Like most movies I enjoyed in the late seventies and eighties, I can't remember much about the movie. I can only remember I liked it and of course it starred Marlene Dietrich. While it doesn't feature Bowie singing there are lots of shots of him.
For me though his most memorable performance was in Merry Christmas Mr Lawrence. This is a clip featuring 'the kiss'. You could skip to 1:10 to see that, but I suggest you watch the whole clip to get some context. It truly is a brilliant performance by Bowie and especially actor Ryûichi Sakamoto, who also composed the at times chilling music for the movie. Watch Sakamoto's eyes as he is kissed. Just brilliant.