Here are the eighteen miniature portraits of Romanov rulers depicted on the Romanov Tercentenary Egg. The only Tsar not present on the Egg is Ivan VI, who as a 2 month old baby officially was Tsar for a short time. He and his mother Anna however were overthrown and Elizaveta, daughter of Peter the Great was installed as Czarina.
Another person who perhaps should be in this list is Michael, the younger brother of Nicholas II. When Czar Nicholas II abdicated in 1917, he did this in favor of his younger brother. Michael had the idle hopes that the Russian people would choose him as ruler, however after only one day, he too abdicated, and was never installed as Czar.