Here are my favorite movies in this genre for each letter of the alphabet:

A – Arachnophobia (1990)

B – The Birds (1963)

C – Cujo (1983)

D – Dinocroc vs. Supergator (2010)

E – Empire of the Ants (1977)

F – Food of the Gods (1976)

G – The Giant Spider Invasion (1975)

H – The Host (2006)

I – It Came from Beneath the Sea (1955)

J – Jaws (1975)

K – Kingdom of the Spiders (1977)

L – Lake Placid (1999)

M – Mosquito (1994)

N – Night of the Lepus (1972)

O – Orca (1977)

P – Piranhaconda (2012)

Q – Queen Crab (2015)

R – Reptilicus (1961)

S – Squirm (1976)

T – Tremors (1990)

U – Up from the Depths (1979)

V – Vipers (2008)

W – Willard (2003)

X –

Y – Yongary, Monster from the Deep (1967)

Z – A Zombie Croc: Evil Has Been Summoned (2015)