Do Bangladeshi citizens need a transit visa in Malaysia?

Timatic, the database used by Airlines, states:

TWOV (Transit Without Visa): Visa required, except for Holders of onward tickets for a max. transit time of 24 hours, arriving at and departing from Kuala Lumpur (KUL). (SEE NOTE 51542) NOTE 51542: Transit without a visa is not possible between Main Terminal and KLIA2.

So, if you change at Kuala Lumpur (and no other Malaysian airport) and the flights arrive and leave from the same terminal, then you do not Need a Malaysian transit visa.

@Alendri You got it wrong. You say OP needs a transit visa if they don't leave the transit area, and needs a tourist visa if they do. That's wrong. What it says is that OP needs no visa if they don't leave the transit area, but needs a transit visa if they do

Citizens of India/Bangladesh/Pakistan/SriLanka (Indian sub-continent) do not need transit visa for upto 120 hours, based on the conditions below:

According to the Malaysian government:

TRANSIT WITHOUT VISA FOR CITIZENS OF BANGLADESH, PAKISTAN, INDIA AND SRI LANKA (INDIAN SUB CONTINENTAL COUNTRIES)

CONDITIONS FOR APPROVAL OF TRANSIT WITHOUT VISA FACILITY
1. Transit Without Visa (TWOV) facility is not offered other than to Indian Sub-Continental Countries citizens.
2. TWOV cannot be given to visitors who do not possess visa from 3rd country of destination as follows:
   · Australia
   · New Zealand
   · United States of America
   · Japan
   · China
   · Taiwan
   · South Korea
3. TWOV facility cannot exceed more than 120 hours (5 days).
4. TWOV facility is not available at entry point other than Kuala Lumpur International Airport (KLIA) and Low Cost Carrier Terminal (LCCT).
5. TWOV cannot be offered to passenger sponsored by airlines other than Malaysia Airlines and Air Asia. At present only MAS and Air Asia have agreed and accepted all terms and conditions imposed by the Malaysian Government.
6. TWOV cannot be given to visitors who do not fulfil the following:
   · Valid national passport or internationally recognized travel document;
   · Travel documents valid for more than six (6) months from the date of entry;
   · A return ticket to country of origin;
   · Not listed in the Immigration Department’s suspected list.
7. There will be no extension of TWOV facility.
8. Permanent resident and long term pass holder are not bound to any of the TWOV regulations and condition stipulated above.

According to Malaysian Immigration Department you require a VISA to enter Malaysia.

However on their page about types of Visa they also state that:

3 Transit Visa

This is issued to foreign nationals who require a visa to enter Malaysia on transit to other countries. Foreign nationals on transit without leaving the airport premises and who continue their journey to the next destination with the same flight do not require a transit visa.

So I would say that if you're not going to leave the airport then you apply for the transit Visa. If you wish to use a hotel or so outside of the airport you do need to have the tourist Visa. Remember that you have your continued traveling tickets ready before you get there so you can prove that you are traveling onwards.

Either Visa costs 20RM for a Bangladesh national.