Here’s a classic list of words with silent letters:
A as in aisle
B as in bdellium
C as in ctenoid
D as in djinni
E as in eye
F as in halfpenny (pronounced “hayp’ny”)
G as in gnat
H as in heir
I as in parliament
J as in marijuana
K as in knot
L as in calm
M as in mnemonic (the first one)
N as in solemn
O as in people
P as in ptarmigan
Q (no known examples)
R as in dossier
S as in island
T as in tsunami
U as in gauge
V (no known examples)
W as in wreck
X as in faux
Y as in beyond
Z as in laissez-faire