This unknown mark can be found, for instance, on the 1 sentimo coin (KM#238). 
This unknown mark can be found, for instance, on the 5 piso coin (KM#272). 

Please, help me identifying these marks

Sometimes there is nothing to be found about a mark. If you have any information about these marks, please contact me. An acknowledgement will be added.

Andorra

This mark (MFC) can be found on a 10 diners 1986 coin
This mark can be found on the coin of 10 diners from 1993: KM# 86

Bhutan

These markings appear on Bhutanese KM# 80 and 83 and maybe more. It looks like a legend in Dzongkha, but it is not quite the same

Colombia

This mark can be found on the 1 peso coin from 1974-1981 just left of the right shoulder of Bólivar. It looks like an 'E' or a 'w'. Maybe it is part of the design, but I think it just might be a designer mark.

Czechoslovakia

Some sort of spade can be seen on the bottom of a 100 korún from 1983 (KM# 108). 

Ethiopia

Monogram of "CV", found on 10 and 20 birr coin from 1966

Haiti

These initials look like 'FG' and can be found underneath the head of Jean-Claude Duvalier on a Haitian 5 centimes coin (KM# 119)

Isle of Man

This mark can be found on the ounce gold Mancunian coin from Isle of Man of 2016 (maybe other coins as well). It looks like a letter "U" in a hexagon

Philippines

Found, for instance, on the 5 piso coin (KM#272). 

Switzerland

Found on the famous Swiss 1935 20 francs gold coin (KM# 35) in combination with the Bern (CHE) mint mark. Nobody seems to know what the letter stands for. Maybe a reference to the designer Fritz Ulysse Landry?

Sweden

I found this mark on a Swedish 1 krona coin, KM# 814, just underneath the head of King Gustaf V. It is probably a designer mark and it looks a mirrored 'E' with an 'L' attached and a dot above.

Turkey

​Probably for foreign trade only. Looks like two towers or castle.