Identify this beetle from Bangladesh
This appears to be some species of beetle (order Coleoptera) in the Bostrichidae family.


Commonly called auger beetles, false powderpost beetles, or horned powderpost beetles. 


 

 Xylopsocus capucinus 

Identification to species can be difficult, but fortunately for you Sittichaya et al (2009) created an illustrated key for IDing species associated with South Asia. 

Based on their key and visual characteristics of your specimen, my guess is that your specimen is Xylopsocus capucinus



 Source: Sittichaya et al 2009 . a. lateral view; b. elytral declivity; c. intercoxal process of the 1st abdominal ventrite; d. dorsal view.


Description: 3-5.5 mm long; 1.4-1.7 mm wide. Shape is cylindrical and similar in general appearance to other common species of the family Bostrichidae. 
Distribution: throughout South and Southeast Asia from India to the Indonesian archipelago.
Hosts: apparently polyphagous attacking almost any woody plant in suitable condition. 
Phenology: adults emerge mainly
between May and November.


Like most false powderpost beetles, the head cannot be seen from above as it is downwardly directed and hidden by the thorax:



 Source: UFL IAFS 



Sources:


Sittichaya, W., Beaver, R., &amp; Ngampongsai, A. (2009). An illustrated key to powder post beetles (Coleoptera, Bostrichidae) associated with rubberwood in Thailand, with new records and a checklist of species found in Southern Thailand. ZooKeys, 26, 33.
Woodruff RE, Gerberg EJ, Spilman TJ (2005). A False Powder-post Beetle, Xylopsocus capucinus (Fabricius)
(Insecta: Coleoptera: Bostrichidae). University of Florida, IFAS Extension Publication No. EENY-179.
Institute of Food and Agricultural Sciences, University of Florida, 4 pp