apex:variable

<!-- For this example to render properly, you must associate the Visualforce page 
with a valid contact record in the URL. 
For example, if 001D000000IRt53 is the contact ID, the resulting URL should be: 
https://MyDomain_login_URL/apex/myPage?id=001D000000IRt53
See the Visualforce Developer's Guide Quick Start Tutorial for more information. -->
         
<!-- Page: -->
<apex:page controller="variableCon">
    <apex:variable var="c" value="{!contact}" />
        
    <p>Greetings, {!c.LastName}.</p>
</apex:page>

/*** Controller ***/
public class variableCon {
    Contact contact;

    public Contact getContact() {
        if (contact == null){                      
        contact = [select LastName from Contact where 
            id = :ApexPages.currentPage().getParameters().get('id')];
        }
        return contact;
    }
}