I would say all Christian denominations mention the 144,000, and have some view of who that is/will be.
Some believe they will be Christians of Hebrew descent, from the 12 tribes.
Some believe the number represents all of the redeemed of earth, from Adam on.
Some believe the number represents all those redeemed from the Christian era.
Some believe they will be those who have reached "perfection" in the final days.
Some believe they will be those who are alive to see Christ return in glory.
Etc.
Ellen White was told (according to one account of a vision) that she (if she continued to do God's will) would be with the 144,000. For SDAs, that would exclude the view that the 144,000 will be those righteous believers who will not die before Christ returns.