I've seen quite a few species in my wanderings - if you are going to go to obscure parts of the world then you've got to make an effort to pick up the "difficult" species.
BARN OWLS
Barn Owl :-
alba - UK
schmitzi - Madeira
gracilirostris - Canary Is.
guttata - Europe
detorta ( Cape Verde Barn Owl ) - Cape Verde Is.
affinis ( African Barn Owl ) - Sub-saharan Africa
javanica - SE Asia, Borneo, Java
delicatula ( Australian Barn Owl ) Australia
lulu ( Pacific Barn Owl ) - Fiji
pratincola ( American Barn Owl ) - Nth. America
furcata ( Caribbean Barn Owl ) - Cuba
contempta - Venezuela
Ashy-faced Barn Owl - Dominican Republic
Sulawesi Masked Owl - Sulawesi
Lesser Masked Owl - Australia
Australian Masked Owl - Australia
Greater Sooty Owl - Australia
African Grass Owl - Sub-saharan Africa
Eastern Grass Owl - India > Australia
Oriental Bay Owl - Malaya, Vietnam
'TRUE' OWLS
Nthn White-faced Scops Owl - Kenya
White-fronted Scops Owl - Malaysia
Reddish Scops Owl - Sumatra, Java
Sokoke Scops Owl - Kenya
Spotted Scops Owl :-
spilocephalus - Nepal
hanbroeki - Taiwan
siamensis - SE Asia
Pallid Scops Owl - Turkey, Israel
Flammulated Owl - British Columbia > California
African Scops Owl - Sub-saharan Africa
Eurasian Scops Owl - Europe > Japan
Oriental Scops Owl - Nepal > Thailand
Ryukyu Scops Owl - Amami-shima > Iriomote-jima
Moluccan Scops Owl - Halmahera, Seram, Buru
Pemba Scops Owl - Pemba I. Tanzania
Indian Scops Owl - India > Thailand
Collared Scops Owl - Heilungjiang, China > Sarawak
Bare-legged Scops Owl - Seychelles
Eastern Screech Owl - Florida
Western Screech Owl - British Columbia > California
Pacific Screech Owl - Costa Rica
Tropical Screech Owl - Costa Rica, Venezuela, Trinidad
Vermiculated Screech Owl - Costa Rica, Venezuela
Cuban Screech Owl - Cuba
Maned Owl - Gabon
Crested Owl - Costa Rica
Spectacled Owl - Venezuela
Great Horned Owl - North America
Eurasian Eagle Owl - W. Europe > Heilungjiang, China
Pharoh's Eagle Owl - Egypt, Israel, UAE
Indian Eagle Owl - N. India
Mackinder's Eagle Owl - Sub-saharan Africa
Spotted Eagle Owl - Kenya
Fraser's Eagle Owl - Gabon
Nduk Eagle Owl - Tanzania
Forest Eagle Owl - Nepal, Nthn. India
Verreaux's Eagle Owl - Sub-saharan Africa
Dusky Eagle Owl - Malaysia
Akun Eagle Owl - Gabon
Blakiston's Fish Owl - Hokkaido, Japan
Brown Fish Owl - India > SE Asia
Tawny Fish Owl - Vietnam
Buffy Fish Owl - Malaysia, Sumatra., Borneo, Vietnam, Thailand
Pel's Fishing Owl - Sub-saharan Africa
Vermiculated Fishing Owl - Gabon
Snowy Owl - Holarctic
Mottled Owl - Trinidad
Brown Wood Owl - Nepal > Borneo
Tawny Owl - UK > Tuva
Humes Owl - Isreal
Barred Owl - British Columbia
Ural Owl - Scandinavia > Japan
Great Grey Owl - Holarctic
Northern Hawk Owl - Holarctic
Collared Owlet - Taiwan
Eurasian Pygmy Owl - Europe, Tuva
Pearl-spotted Owlet - Tanzania, Kenya
Nthn. Pygmy Owl - British Columbia
Californian Pygmy Owl - British Columbia > California
ferruginous Pygmy Owl - Costa Rica, Venezuela
Cuban Pygmy Owl - Cuba
Red-chested Owlet - Gabon
Sjostedt's Owlet - Gabon
Barred Owlet - Thailand
Javan Owlet - Java, Bali
Eastern Barred Owlet - Tanzania
Little Owl - UK > Altai Republic, Morocco > Ethiopia
Burrowing Owl - California, Florida, Dom. Rep., Venezuela, Argentina
Tengmalm's Owl - Holarctic
Nthn. Saw-whet Owl - British Columbia
Powerful Owl - Victora, Australia
Barking Owl - Halmahera, Queensland
Sthn. Boobook - Australia
Morepork - New Zealand
Nthn Boobook ( brown Hawk Owl ) - Japan > Borneo
Moluccan Boobook - halmahera, Seram, Buru
Speckled Boobook - Sulawesi
Striped Owl - Costa Rica
Long-eared Owl - Holarctic
Stygian Owl - Cuba, Dom. Rep.
Abyssinian Owl - Ethiopia, Kenya
Jamaican Owl - Jamaica
Short-eared Owl - Holarctic, Falklands
Marsh Owl - Morocco, Sub-saharan Africa