NAL Nakanihon Airlines, Nagoya, Japan, 1988-2007 renamed as Air Central.   - #1:

Namib Air, Windhoek, Namibia, 1966-1991  renamed to Air Namibia.  - with thanks to Gerd Clemens - #1:

Nasair, Asmara, Eritrea, founded 2006.  - with thanks to Dr. David Bradford - #1:

Nasair, Riyadh, Saudi-Arabia, founded 2006. - #1:

National Airlines, Miami, Florida, USA, 1934-1980 merged into PanAm.
#1  and   #2- outstanding for its shopping bag size of 38 x 24,6 cm.

NATO - (fetched from Royal British Airforce)        #1           and  #2:

Nature Air, San José, Costa Rica, founded 1991.  - with thanks to Bruce Kelly -#1:

Necon Air, Kathmandu, Nepal, 1992 - 2003.       #2:

NEOS, Milano, Italy,  founded 2001.
  - with thanks to Nicola Carmignani   #2,   - to Gerd Clemens - #1:

Nepal Airlines, Kathmandu, Nepal, founded 2006 by renaming from Royal Nepal Airlines(q.v.).  #2:

Nesma Airlines, Cairo, Egypt, founded 2010.         - #2,          #3:

New Gen Airways, Bangkok, Thailand, founded 2012.  
-  #1    rear                                                and                              front:

Nextjet, Solna, Sweden, founded 2002.  #1 - this bag is to be considered as real Multi-bag, with fold out handles.

NFD = Nürnberger Flug Dienst, Nuremberg, Germany, 1974-1993, merged with Eurowings(q.v.):

NHT, Porto Alegre, Brazil, founded 2006.     - #1,            #3:

NIKI Airlines, Vienna, Austria, founded 2003.    - #1,        and         #2:

NLM, Amsterdam, Netherlands, 1966-1992.    #1   and    #2:

Nordeste Varig, Rio de J., Brazil, 2006-2008. During bankruptcy protection
until integration into GOL(q.v.) the Nordeste name was revived by split part "old" Varig.  # 1:

Northwest Airlines, Eagan, Minnesota, USA, 1949-2010. During 1949-1986 branded as Northwest Orient,
2010 merged into Delta Airlines(q.v.).   -   Northwest  #2 (24x12cm)    and     #11 (21,6x14,1cm):

Northwest      #  7           and                       #4:

 Northwest Orient  # 3    and             #7: 

#5a,                       and                   -   #6/#2/#1(diff size of stripes):

Norwegian Air Shuttle, Fornebu/Oslo, Norway, founded 1993.  -
#2(pointed base, tear off strip)/#3(flat base, no tear off strip),            #1,             and    #5:

Nouvelair, Monastir, Tunesia, founded 1989.         -    #1,        #5,        #2,             #9:

#11:

Nova Airways, Khartoum, Sudan, founded 2000.   - #1:

NOVAIR, Stockholm, Sweden, founded 1997.           
-          #1,                                          #3,                               # 5:

Novair, London, UK, 1988-1990.  Successor of Cal Air (q.v.)

NOVO AIR, Dhaka, Bangladesh, founded Jan 2013.     -   #1: