longest ruling Romanov?

[helenazar]

But who was the longest ruling? Was it Catherine II (1762-1796)?

[AGRBear]

But Catherine II was not a Romanov nor were any Tsars after her rule?

Trick question  

And, Emp. Michael I Alexandrovich ruled from the moment the ink was wet on the abdication of Nicholas II until he was murdered by Bolsheviks in 1918.  [I've forgotten what number he was when using the title of Tsar....]  His manifesto to the Prov. Govt. was not an abdication....  

AGRBear

[helenazar]

But Catherine II was not a Romanov ...

She was considered a Romanov, even though technically, she wasn't, but neither was her husband Peter III...

[hikaru]

Longest were Peter the Great and Catherine II
Peter the Great ( 1689-1725)
Catherine ( 1762-1796)
I think so.