Too many to count
There are literally hundreds of organic compounds which, when burned, become the "tars" that stain your fingers, the filter (and your lungs).
Cigarette smoke, in addition, to nicotine
, also contains formaldehyde
and carbon monoxide. Cigarette companies put in flavoring agents, menthol and other things, and actually the nature of these are considered trade secrets and they don't have to list them.