"Power" is a bit ambiguous of a meaning for us to attribute, but the use of crocodiles in symbolism is far from unheard of. The god Sobek (also known as Sebek, Sobk, and Suchos) certainly fits the bill and many things were made in his image; not just in Egypt but even so far as coins minted in the late Roman Republic.
"The crocodile was specifically selected for Cleopatra Selene by Cleopatra VII, and that this selection was intended to recall a significant event that occurred at the foundation of the Ptolemaic dynasty, comprising part of a wider strategy of reconstituting the empire of Ptolemy I Soter and Ptolemy II Philadelphos. As a result, the image was subsequently utilized on Octavian's gold and silver AEGVPTO CAPTA coinage, the bronze Nemausus coinage, and the coinage of Juba II of Mauretania, all of which either alluded to, or directly referred to, Cleopatra Selene."
{Acta Classica : Proceedings of the Classical Association of South Africa, Volume 55, Issue 1, Jan 2012, p. 43 - 56}
'The Oxford Handbook of Roman Egypt' tells us that Sobek was later hellenized as well.
"The concept [Sobek as a] warrior god was one of the leading in Kom Ombo. The theologians of the temple used the imagery and epithets of Sobek as a terrifying crocodile to represent him in the role of a horrible warrior animal in hymns 92, 58 and the Double Hymn: “Living crocodile, which strikes the rebels, the Terrifying, who devours the companions of Apophis." Among Sobek's main warrior pithets are: rȝ-ḥs (“the terrific throat”) and ḥs-ḥr (“terrific of face”). "
{Christian Leitz, “Der Lobpreis des Krokodils: drei Sobekhymnen aus Kom Ombo” in: Hermann Knuf, Christian Leitz and Daniel von Recklinghausen (eds), Honi soit qui mal y pense: Studien zum pharaonischen, griechischrömischen und spätantiken Ägypten zu Ehren von Heinz-Josef Thissen (Leuven: Peeters, 2010) 291-355}
{Adolphe Gutbub, Textes fondamentaux de la théologie de Kom Ombo. [T.] 1, 15}
Parker's Glossary of Heraldry does have an entry for Alligator with two examples:
Alligator, and Crocodile. The only case of either of these borne in English arms is,
Gules, a chevron argent between three alligators .... --HITCHCOCK.
Per chief gules and or, in base an olive-tree eradicated and fructed proper, in chief the head and fore-legs of a crocodile issuant proper--DALBIAC, Bedford.
I'm fairly sure I've seen crocodiles or alligators in coats of arms for something African or Australian (cities, maybe?), but I'd guess they were 20th century uses. Parker's was published in 1894, with the blazons listed usually being much older.
Burke's General Armory (1864) lists several more heraldic alligators, including one for Rossiter/Rauceter/Roucester that has some differences (changes in arms between different branches of the family) with a "lizard or alligator," as if they were interchangeable. You can see some older heraldic lizards here, on an SCA page for "reptile".