CREATE TABLE table_1495 ("Series #" FLOAT, "Season #" FLOAT, "Title" TEXT, "Directed by" TEXT, "Written by" TEXT, "Original air date" TEXT, "U.S. viewers  ( millions ) " TEXT)

Name the directed by for 15.15 viewers
SELECT "Directed by" FROM table_1495 WHERE "U.S. viewers (millions)" = '15.15'
SELECT "Directed by" FROM "table_1495" WHERE "U.S. viewers (millions)" = '15.15'