Balancer

a person or thing that balances.
Entomology, halter2 .
an acrobat, rope-dancer, or tumbler.
Contemporary Examples

Almost all Asian nations want America as the balancer and protector against an increasingly demanding Beijing.
Obama’s Next Headache Leslie H. Gelb November 2, 2010

Historical Examples

In the long run Honour, confound it, got a bit of a balancer which helped it to win.
The Recipe for Diamonds Charles John Cutcliffe Wright Hyne

The arrangement forms a cheap and effective substitute for a balancer set, but lacks the adjustable properties of the latter.
Hawkins Electrical Guide, Number One Nehemiah Hawkins

What I hope to accomplish, explained Mr. Morse, is to construct a combined steerer and balancer on one lever.
Airship Andy Frank V. Webster

It just caught the outspread furry tail, which was serving as a rudder and balancer to that adventurous flight.
Neighbors Unknown Charles G. D. Roberts

Depend upon it, sir, the balancer that remains shall be faithfully paid.
London’s Heart B. L. (Benjamin Leopold) Farjeon

When the elevated cell of the balancer was filled, its weight caused it to fall.
Practical Cinematography and Its Applications Frederick Arthur Ambrose Talbot

In Stringfellow’s and Tatin’s models the main aerofoil and balancer (tail) are practically contiguous.
The Theory and Practice of Model Aeroplaning V. E. Johnson

noun
a person or thing that balances
(entomol) another name for haltere