Bitcoin and Variants and short forms:

BTC - Bitcoin

LTC - Litecoin

NMC - Name Coin

NVC - Novacoin

TRC - Terracoin

PPC - Peer-2-Peer Coin

FTC - Feathercoin

CNC - Chinacoin

 there are many more but most popular are  listed above. 

Amongst them.

1) BTC  is at one aimed at 21 million bitcoins is reached around the year 2140.

2) LTC

3) PPC