Variants of a mold are catalogued separately, so each one has its own sets and minifigs. Check these too if something you expect is missing here.

• 28621 Minifig Head [Plain] [Vented Stud - 2 Holes] this part is a mold of it
• 3626a Minifig Head [Plain] [Solid Stud] this part is a mold of it
• 3626b Minifig Head [Plain] [Blocked Open Stud] this part is a mold of it
• 3626c Minifig Head [Plain] [Hollow Stud] this part is a mold of it
• 6947pr0001 Minifig Head Tin Man, Robot Metal Plating Print of this part
• 6947pr0002 Minifig Head Santa, Gold Eyebrows and Beard, Smile Print Print of this part
• 6947pr0003 Minifig Head Cooper, Droid, Black Dots, Black/Metal Blue Eyes / Yellow Face, Smirk Print of this part
• 6947pr0004 Minifig Head Bruce Wayne, Eyebrows, Chin Dimple, Frown / Angry Print Print of this part
• 6947pr0005 Minifig Head Doctor Doom, Metal Plating, Black Lined, Ribbits, Medium Brown Around Eyes Print of this part