What is another word for a sure person?

There are many words you could use to describe a "sure" person, depending on the specific aspect you want to emphasize:

Confidence:

* Confident

* Self-assured

* Bold

* Assertive

* Poised

* Unwavering

* Fearless

Reliability:

* Reliable

* Dependable

* Trustworthy

* Stable

* Consistent

* Solid

Determination:

* Determined

* Resolute

* Persistent

* Tenacious

* Unflinching

* Unyielding

Other options:

* Certain

* Assured

* Firm

* Strong-willed

* Dogged

The best word will depend on the specific context and the nuances of the "sureness" you want to convey.