Of course:

A is the circumflex*.
B is an inverted apostrophe*. I don't think it's used anywhere, but it was the most similar I could get.
C is cedilla†.
D is a flipped apostrophe*. Don't think it is used, like with B.
E is a diaeresis/umlaut/trema‡.
F is a hook* as in Seereer Ƈ.
G is an apostrophe/smooth breathing sign*.
H is a macron*§.
I is a dot above*.
J is a dot below*.
K is a diagonal stroke* as in Danish Ø.
L is a stroke† as in Polish Ł.
M is an ogonek¤
N is a tilde*‡¤.
O is a ring above*‡.
P is a rough breathing sign*.
Q is a hook* as in Vietnamese Ả.
R is an acute accent*.
S is an inverted breve*.
T is a stroke*.
U is a breve*.
V is a caron*.
W is a double acute accent*.
X is a double grave accent*.
Y is a horn*.
Z is a grave accent*.

* because of the similar shape.
† because they are used together.
‡ because the diacritic is derived from the letter.
§ because a vowel followed by an h can be interpreted as a long vowel, which is often signified by a macron.
¤ because it signifies a nasal vowel.