Identify the next term in the given letter series:
C, E, G, K, M, ?

Let us look at the alphabetical positions of the given letters:
* $\text{C}=3$
* $\text{E}=5$
* $\text{G}=7$
* $\text{K}=11$
* $\text{M}=13$

The positional values $3,5,7,11,13$ form a series of consecutive prime numbers. The next prime number after $13$ is $17$.
The letter at the $17\text{th}$ position in the English alphabet is $\text{Q}$.