I have a species that is warlike almost all the time due to tribal wars between each other (and other reasons). If they're almost always fighting would they be interested in making things that have no purpose other than to be looked at?
It heavily depends on Your personal definition of "art", but any known warlike culture has been (or "is") fond of music, songs (mostly ballades) and dance.
Many of them also delight in poetry, sculpture, painting etc.
... although all these tend to be vastly mono-thematic ;)
NOTE: You seem to be deceived by a single (apparent) counter-example: Spartans. They did not leave behind any major artifact, but:
- this doesn't mean they did not have their art forms (e.g.: singing and dancing)
- this was not due to their warlike culture, but to their refuse of any indulgence to the "pleasures of life" (think: what major artifact do we have from medieval hermits? They surely weren't warriors, but left more-or-less the same kind of remains as Spartans)
Have you ever admired the motion that exists in a well performed kata, and ever compared it to a dance?
How about looking closely at the art inherent in a coat of arms?
Or the Beauty of a finely crafted Axe?
One thing that combat, War, and the arts have in common is passion.
There is no reason why art wouldn't have a prominent place in such a society. It would probably skewed. Like a little more Wagner in the music, More paintings of Washington crossing the Potomac, and the equestrian statue code is real.
Art might be very therapeutic for a species used to tumult, an act of imagination giving an altered sense of reality.
It might also play a role in combating cowardice and strengthening visions of who is friend and who is foe.
It might also just be fun, if they have time for that.
I would say yes.
Take the Bayeux Tapestry for example, while the Normans definitely weren't a purely warlike culture as you seem to be suggesting, the Bayeux Tapestry is a record of their abilities in battle and their successful conquest of England.
If they are religious than they will almost certainly make art to celebrate their god(s), historically a lot of art was religious in theme and just because your species is particularly warlike doesn't mean they won't create art to honour their gods.
Even races that were seen as very warlike or bloodthirsty (Vikings, Goths, Aztecs) created art in various forms.
That is entirely up to you.
we are not really sure why art evolved, the best guess at this point is that it is a way of putting your intelligence, creativity, and skill on display. A mate can't just see your intelligence it needs to be displayed with some activity. Your creatures may not have art or may have art in the form of sparing dance, weapon creation, or even landscape drawing. It might have the full human form we enjoy with all its diversity. their proclivity for war will not have much impact whether they have art it will just affect the content of their art.
FYI the first art we know of for humans were giant hand axes, exaggerated oversized(to the point of uselessness) examples of everyday tools that help display the artist's skill in stone knapping.
Certain types of art can be used to create a feeling of esprit de corps amongst a group of people or even a nation.
Statues of the heroes of old can be used to inspire thier successors to match their deeds or exceed them.Paintings can serve the same purpose. They can also be used as records of glorious victories in honour of those that achieved them, take Trajans Column in Rome that records the victory of Trajan in Dacia. It also depicts many of the tactics he used to win the war some might have another purpose to record how it was done.
Some arts can have a direct use to the military, take marching bands who were originally used to keep troops in step when marching, raise their morale and to send signals. Now the can be great displays like the Edinburgh Tatoo.