The following list of Russian Conquistadors (Cossacks) and Explorers is from EU 1.08 and the IGC 1.7c files:
Name: Dates: Statistics:
Stroganov(C) 1560 - 1575 9/3/1/1/0
Hetman (C) 1565 - 1570 8/2/3/4/0
Mosalski (C) 1565 - 1570 9/3/1/1/0
Yermak (C) 1575 - 1600 8/5/6/6/0
Kolstov (C) 1580 - 1605 8/5/2/2/0
Beketov (C) 1630 - 1640 8/3/3/2/0
Mosquitin (C) 1630 - 1640 8/4/2/2/0
Dezhnev (E) 1635 - 1655 8/5/2/2/0
Poyarkov (C) 1640 - 1660 9/4/3/3/0
Khabarov (C) 1680 - 1690 8/4/4/4/0
Gagarin (C) 1700 - 1715 8/5/3/3/0
Chelyushkin (C) 1725 - 1745 9/5/2/3/0
Behring (E) 1725 - 1740 5/5/4/2/0
De Long (E) 1750 - 1770 6/3/2/2/0
Baranov (C) 1765 - 1790 8/5/4/4/0
C = Conquistador, E = Explorer
Stats are: Rank/Maneuver/Fire/Shock/Siege
You can also get 'random' Explorers: I got one as early as 1510 in Ingermannland. If you have Random Events on, it may include an earlier death than shown for some of the explorers, leader, conquistadors, or monarchs. Explorers show up automatically with a Warship, Conquistadors with 1000 troops. Note that some of the 'Conquistadors' are pretty darned good Commanders, like Yermak, Khabarov, or Baranov. If you don't have anything to explore with them, put them in charge of an army and kick some civilized butt!