Let's go with people who have experience on the subject.
Goku
Commander Shepard (with Garrus, Tali, Legion, and Wrex because they're my favorites)
The Doctor
Gordon Freeman
...Technically that's eight. Oops. Well... If there's really no room on the ship (or TARDIS), then throw out Tali because she and Legion basically do the same thing and at least Legion has more durable armor, no immune system to worry about, and if the platform fails, at least all 1000+ active programs can upload themselves into my cellphone or something.
Nikolaz72 said:
The Engineer. From Battlefield.
Commander Sheperd (as Engineer). From Mass Effect (1)
A Marine (With Turrets). From Aliens. - This guy needs to scream Game Over.
Leonardo Davinchi. From Assasins Creed. - This guy technically counts as Engineer.
The Engineer. From Sanctum
The Engineer. From Global Agenda.
Tali (Engineer) From Mass Effect 2.
Hmm... Think you have enough engineers? Surely you could squeeze in a few more!