The Brown Shrike (Lanius cristatus) is a bird in the shrike family that is found in Asia.
Like most other shrikes, it has a distinctive black "bandit-mask" through the eye and is found mainly in open scrub habitats, where it perches on the tops of thorny bushes in search of prey.
Females have fine scalloping on the underside and the mask is dark brown and not as well marked as in the male. 
Juveniles are more whitish or grayish below, with heavy barring on sides and flanks.
There are 4 subspecies which differ in plumage being slightly darker brown, more reddish in the tail or with or without a grey crown.
The 1-3 photos show a juvenile, either from the subspecies Lanius cristatus cristatus or Lanius cristatus superciliosus which both occur in Vietnam.
The 4-5 photos show a female of the subspecies Lanius cristatus cristatus which has a white anal area instead of greyish as in Lanius cristatus superciliosus.

1st, 2nd & 3rd photo: Tam Coc, Ninh Binh, Vietnam, 9 January 2024
4th & 5th photo: Hoi An area, Vietnam, 29 December 2023