Find the missing character?

E
F
G
H

The missing character is $\boxed{\text{F}}$.

The sequence is a list of letters, each of which is one more than the previous letter. The first letter is $\text{A}$, and the second letter is $\text{B}$. The third letter is $\text{C}$, which is one more than $\text{B}$. The fourth letter is $\text{D}$, which is one more than $\text{C}$. The fifth letter is $\text{E}$, which is one more than $\text{D}$. The sixth letter should be $\text{F}$, which is one more than $\text{E}$. However, the sixth letter in the sequence is $\text{G}$. This is incorrect, because $\text{G}$ is not one more than $\text{E}$. The correct sixth letter should be $\text{F}$.