Is the Nahkriin mask needed to get the last mask in Skyrim?

I really want to get the last mask! I don't know if the Nahkriin mask is needed or not and I am getting really confused!

Do I need the Nahkriin mask in order to obtain the last mask? I'm playing on Xbox if it matters.

Solution 1:

The Nahkriin mask is indeed needed to get the Konahrik mask.

http://elderscrolls.wikia.com/wiki/Wooden_Mask states (emphasis mine):

A bust is available for the following masks:

• Volsung's Bust (see Volsung, Volsung Mask)
• Vokun's Bust (see Vokun, Vokun Mask)
• Otar's Bust (see Otar, Otar Mask)
• Morokei's Bust (see Morokei, Morokei Mask)
• Rahgot's Bust (see Rahgot,Rahgot Mask)
• Nahkriin's Bust (see Nahkriin, Nahkriin Mask)
• Hevnoraak's Bust (see Hevnoraak, Hevnoraak Mask)
• Krosis' Bust (see Krosis, Krosis Mask)

Once the eight masks are placed in each respective bust on the shrine, the final mask Konahrik is revealed. The other masks may be taken from the shrine once Konahrik is obtained.

This page clearly include Nahkriin's mask as a required mask.