These drawings of sea monsters, taken from books written in Europe centuries ago, prove that you don't need CGI to create a seriously incredible creature.

An aquatic lion, pig and elephant from the ceiling of Church of St. Martin in Zillis, Switzerland, 12th century

(via Monster Brains)

A crocodile from Liber Floridus (Book of Flowers), an encyclopedia by Lambert, Canon of Saint Omer between 1090 and 1120.

(via Erik Kwakkel)

A crocodile from the Rochester Bestiary, c. 1225-1250

(via Wikimedia Commons)

A lobster-fish hybrid from Ortus sanitatis, by Jonathan Prüss, 1499

(via Internet Archive)

Whales, sea pigs, orcas, sea serpents and other monsters on Carta Marina, a map by Olaus Magnus, 1527-1539

(via Wikimedia Commons)

The famous Sea Monster chart of Sebastian Münster, one of the most influential works of 16th century, created in 1539

(via Wikimedia Commons)

A sea serpent and a hydra from Konrad Gesner's Historiae Animalium, 1558

(via National Library of Medicine)

A sea-pig from La descriptione dela Puglia, 1567

(via Newfilmkritik)

Two giant fishes attacking a ship off the coast of America, in a map from the first true modern atlas named Theatrum Orbis Terrarum, written by Abraham Ortelius, first printed in 1570

(via Columbia University)

A giant squid, whales, a sea serpent and some monsters from Adriaen Coenen's Visboek, 1580

A monkfish:

The Tigruis, a half-blind monster who loves to follow ships, because it "likes to watch the sails being hoisted":

(via National Library of the Netherlands)

St. Brendan holding a mass on the back of a whale from Nova typis transacta navigatio novi orbis Indiæ occidentalis, by Bernardo Buil in 1621

(via Streets of Salem)

A marine dragon from Monstrorum Historia, by Ulissi Aldrovandi, first published around 1642

(via Paul K)