We know of two international lists that are maintained by reputable agencies; try these if you don't find what you're looking for below:
The International Association for Suicide Prevention maintains a Global Crisis Centre Directory..
The Befrienders maintain a hotline database; use the "Find a Helpline by Country" control at the top of their page.
United States
National Suicide Prevention Lifeline: 1-800-273-8255 (TALK) Veterans press 1 to reach specilised support.
(The older number, 1-800-SUICIDE, is no longer published by the lifeline agency and will probably stop working in the near future.)
Online Chat: http://www.suicidepreventionlifeline.org/gethelp/lifelinechat.aspx
Crisis Text Line: Text "START" to 741-741
Spanish: 1-800-SUICIDA
EU Standard Emotional Support Number 116 123 - Free and available in much of Europe, details here
Australia
13 11 14 https://www.lifeline.org.au/Get-Help/Online-Services/crisis-chat
Austria
142, Youth 147 Online: http://www.onlineberatung-telefonseelsorge.at
Belgium
02 649 95 55
Brasil
141
Canada
Kids Help Line (Under 18): 1-800-668-6868
Alberta: 1-866-594-0533
British Columbia: 1-888-353-2273
Manitoba: 1-888-322-3019
New Brunswick: 1-800-667-5005
Newfoundland & Labrador: 1-888-737-4668
Northwest Territories: 1-800-661-0844 7pm-11pm everyday
Nova Scotia: 1-888-429-8167
Nunavut: (867) 982-0123
Ontario: 1 800 452 0688
Prince Edward Island: 1-800-218-2885 (Bilingual)
Quebec: 1-866-277-3553 or 418-683-4588
Saskatchewan: (306) 933-6200
For more numbers in all areas please see here
Deutschland
0800 1110 111
Denmark
70 20 12 01
France
01 40 09 15 22
Greece
1018 or 801 801 99 99 Greece - http://www.suicide-help.gr/
Iceland
1717
India
91-44-2464005 0
022-27546669
Iran
1480 6am to 9pm everyday
Ireland
ROI - local rate: 1850 60 90 90
ROI - minicom: 1850 60 90 91
Israel
1201
Italia
800 86 00 22
Malta
179
Japan
03-3264-4343
3 5286 9090
Korea
LifeLine 1588-9191
Suicide Prevention Hotline 1577-0199
Mexico
Saptel 01-800-472-7835
Netherlands
0900 1130113 www.113online.nl
New Zealand
0800 543 354 Outside Auckland
09 5222 999 Inside Auckland
Norway
Kirkens SOS offers phone support and chat: 22 40 00 40 and http://www.kirkens-sos.no/
Osterreich/Austria
116 123
Romania
116 123
Serbia
0800 300 303 or 021 6623 393
Online chat:http://www.centarsrce.org/index.php/kontakt[2]
South Africa
LifeLine 0861 322 322
Suicide Crisis Line 0800 567 567
Spain
http://www.telefonodelaesperanza.org/
Suomi/Finland
010 195 202 available 9am-7am weekdays and 3pm-7am weekends 112, the regular emergency line, may be used at other times
Sverige/Sweden
020 22 00 60
Switzerland
143
UK
Samaritans (www.samaritans.org)
Voice: 116 123 (24/7 Free to call, will not appear on phone bills, formerly 08457 90 90 90)
Text: 07725909090
Email: [email protected]
Helplines for Men from thecalmzone.net:
Voice: 0800 58 58 58 (5pm to midnight nationwide, also 0808 802 58 58 London and 0800 58 58 58 Merseyside)
Text 07537 404717 (5pm to midnight, start your text with CALM2)
Online Chat: https://www.thecalmzone.net/help/get-help/
ChildLine (childline.org.uk), for those 19 and under:
Voice: 0800-11-11 (Free to call, does not appear on phone bills)
Online Chat: http://www.childline.org.uk/Talk/Chat/Pages/OnlineChat.aspx
Email: http://www.childline.org.uk/Talk/Pages/Email.aspx
Directory of suicide-related services: http://www.supportline.org.uk/problems/suicide.php
Uruguay
Landlines 0800 84 83 (7pm to 11 pm)
(FREE) 2400 84 83 (24/7)
Cell phone lines 095 738 483 *8483