Sergeant Bertha Blast (voiced by Jo Anne Worley) is a character appearing only in Private Olive Oyl. A diminutive yet loud and commanding Army sergeant, she is in charge of new recruits Olive Oyl and Alice the Goon, whose lack of discipline would often unwittingly cause chaos in the base. Sergeant Blast would be left much annoyed and incensed - especially each time Colonel Crumb showed satisfaction at the pair's actions, oblivious to their earlier blunders.
- Sergeant Blast was most likely based on the character of Captain Lewis, originally played by Eileen Brennan, in both the movie and television series Private Benjamin.
- A running gag is Sergeant Blast being constantly stepped on or trampled.