There are akshara devatas for each akshara of gayatri mantra as follows
1 - Agni
2 - Ashvins
3 - Soma
4 - Vishnu
5 - Savita
6 - Pusha
7 - Marut
8 - Brihaspati
9 - Mitra
10 - Varuna
11 - Indra
12 - Visvedeva
13 - Vasus
14 - Rudras
15 - Adityas
16 - Aditi
17 - Vayu
18 - Bhumi
19 - Antariksham
20 - Dyou (svarga)
21 to 24 - Digdevatas