Builder is a skill that can be given to a lemming. It is the fifth of the eight skills available in Lemmings, as well as the Classic Tribe in Lemmings 2. Builders create a diagonal staircase upwards, consisting of twelve bricks. Once a Builder runs out of bricks, he will shrug his shoulders and continue walking. You can make him build again by selecting him before he walks off the bridge. The lemming will stop and turn back if it bumps into a wall or ceiling. The builder is notable as being the only Classic skill capable of adding terrain to the level, and as such features heavily in solutions to many levels.
In Lemmings: The Puzzle Adventure for mobile phones, builders work in a similar fashion to the other games. However, the stairs they put down are different in being nearly indestructible. They are able to stop falling boulders, and can only be removed by the bomber skill.
- Builders' bridges can be "stretched" by letting the builder walk a few steps after shrugging and building again before falling off the bridge. This technique is required to complete the level The Search for Lem in Holiday Lemmings 1993.
- In the Nintendo NES and Game boy ports, Builders have 16 tiles instead of 12.
- In the Atari Lynx port, Builders have 13 tiles instead of 12.
- In the SNES port, when a Builder runs out of tiles, he will temporarily be referred to a "Waver" before becoming a Walker again.
- In Lemmings 3D, Builders have 6 tiles instead of 12.
- Builders will be deflected by a blocker and continue building upwards in the reversed direction This technique is required to complete the level Down, along, up. In that order.
- In Holiday Lemmings 1993, the Builder's backpack is blue instead of red.