Franck is a small lunar impact crater that lies near the north end of Sinus Amoris, a bay on the northern part of Mare Tranquillitatis.

It was named after German physicist and Nobel laureate James Franck.

[1] The crater lies just to the southeast of Brewster, and farther to the south of Römer.

Franck was previously designated Römer K. This is a circular, bowl-shaped crater with a sharp rim that has not been significantly eroded.

Just to the north of Franck is a joined pair of smaller craters, and the three nearly form a merged cluster of impacts.