Here are all the CPAN distributions that start with the letter X:

X-Osd
X-Protocol
X-Tiny
X10
X10-Home
X11-Aosd
X11-FreeDesktop-DesktopEntry
X11-FullScreen
X11-Fvwm
X11-GLX
X11-GUITest
X11-GUITest-record
X11-IdleTime
X11-Keyboard
X11-korgwm
X11-MinimalOpenGLViewport
X11-Motif
X11-Muralis
X11-PngViewer
X11-Protocol
X11-Protocol-More
X11-Protocol-Other
X11-Resolution
X11-SendEvent
X11-Terminal
X11-Wallpaper
X11-Wcl
X11-WindowHierarchy
X11-WM-Sawfish
X11-WMCtrl
X11-XCB
X11-Xlib
X11-XRandR
x11guitest
X12
X3D
X3D-Debug
X3D-Values-Int32
X500-DN
X500-DN-Marpa
X500-DN-Parser
X86-Disasm
X86-Udis86
Xacobeo
Xango
xanton+xiri
XAO-Base
XAO-Catalogs
XAO-Commerce
XAO-Content
XAO-FS
XAO-ImageCache
XAO-Indexer
XAO-MySQL
XAO-PodView
XAO-Web
XAS
XAS-Collector
XAS-Logmon
XAS-Model
XAS-Service
XAS-Spooler
XAS-Supervisor
Xbase
XBee-API
XBRL
XBRL-JPFR
Xcalibur-Rawfile
XCAP-Client
xchar
Xcode-Project
xcruciate
xcruciate-combined
xcruciate-unitconfig
xcruciate-utils
xcruciate-xcruciateconfig
xDash
xdbfdump
xdbfdump-win32-bin
XDG-BaseDirectory
XDI
XDI-SPIT
XDR
xDT-Parser
Xelig
Xen-API
Xen-Control
Xfce4
XFontSelect
XForms-Generator
Xforms4Perl
XHTML-Instrumented
XHTML-MediaWiki
XHTML-Util
XHTML-Writer
XiaoI
XIRCD
xisofs
XLog
XLog-File
XLS-Simple
xls2csv
XLSperl
XMail-Ctrl
XMail-Install
XML
XML-All
XML-Amazon
XML-Ant-BuildFile
XML-ApacheFOP
XML-API
XML-API-WIX2
XML-APML
XML-AppleConfigProfile
XML-ApplyXSLT
XML-ASCX12
XML-asData
XML-Assert
XML-ASX
XML-Atom
XML-Atom-App
XML-Atom-Ext-Inline
XML-Atom-Ext-Media
XML-Atom-Ext-OpenSearch
XML-Atom-Ext-Threading
XML-Atom-Filter
XML-Atom-FromOWL
XML-Atom-Lifeblog
XML-Atom-Microformats
XML-Atom-OWL
XML-Atom-Server-PSGI
XML-Atom-Service
XML-Atom-SimpleFeed
XML-Atom-Stream
XML-Atom-Syndication
XML-AutoWriter
XML-Axk
XML-Bare
XML-Bare-SAX-Parser
XML-Beautify
xml-binddata
XML-Bits
XML-BMEcat
XML-Builder
XML-Canonical
XML-CanonicalizeXML
XML-CAP
XML-Catalog
XML-Catalogs
XML-Catalogs-HTML
XML-CGI
XML-Chain
XML-Char
XML-Checker
XML-Class
XML-Clean
XML-Code
XML-Comma
XML-CommonNS
XML-CompactTree
XML-CompactTree-XS
XML-Compare
XML-CompareML
XML-Compile
XML-Compile-C14N
XML-Compile-Cache
XML-Compile-Dumper
XML-Compile-Licensed
XML-Compile-RPC
XML-Compile-SOAP
XML-Compile-SOAP-AnyEvent
XML-Compile-SOAP-Daemon
XML-Compile-SOAP-Daemon-Dancer2
XML-Compile-SOAP-Mojolicious
XML-Compile-SOAP-WSA
XML-Compile-SOAP12
XML-Compile-Tester
XML-Compile-WSA
XML-Compile-WSDL11
XML-Compile-WSDL11-Recursive
XML-Compile-WSS
XML-Compile-WSS-Signature
XML-CompileX-Schema-Loader
XML-CompileX-Tranport-SOAPXMPP
XML-CompileX-WSDL11-AsMethods
XML-Conf
XML-Config
XML-Constructor
XML-Crawler
XML-CSV
XML-CuteQueries
XML-Database
XML-Dataset
XML-DB
XML-Debian-ENetInterfaces
XML-Declare
XML-Descent
XML-Diff
XML-DifferenceMarkup
XML-Directory
XML-Diver
XML-DocStats
XML-Document-RTML
XML-Document-Transport
XML-DOM
XML-DOM-BagOfTricks
XML-DOM-Lite
XML-DOM-XML_Base
XML-DOM-XPath
XML-DOM2
XML-DOMBacked
XML-DOMHandler
XML-DoubleEncodedEntities
XML-Driver-HTML
XML-DT
XML-DT-Sequence
XML-DTD
XML-DTDParser
XML-Dumper
XML-Easy
XML-Easy-ProceduralWriter
XML-Easy-SimpleSchemaUtil
XML-Easy-Transform-RationalizeNamespacePrefixes
XML-EasyOBJ
XML-EasySQL
XML-ED
XML-Edifact
XML-Elemental
XML-Enc
XML-Encoding
XML-Entities
XML-EP
XML-EPP
XML-Excel
XML-ExistDB
XML-ExtOn
XML-Fast
XML-Feed
XML-Feed-Aggregator
XML-Feed-Deduper
XML-Feed-Format-hAtom
XML-Feed-JavaScript
XML-FeedLite
XML-FeedPP
XML-FeedPP-MediaRSS
XML-FeedPP-Plugin-AddMP3
XML-FeedPP-Plugin-DumpJSON
XML-FeedWriter
XML-Filter-Base
XML-Filter-BufferText
XML-Filter-Cache
XML-Filter-Conditional
XML-Filter-DataIndenter
XML-Filter-DetectWS
XML-Filter-Digest
XML-Filter-Dispatcher
XML-Filter-DOMFilter-LibXML
XML-Filter-Essex
XML-Filter-ExceptionLocator
XML-Filter-EzPod
XML-Filter-GenericChunk
XML-Filter-Glossary
XML-Filter-Hekeln
XML-Filter-Mode
XML-Filter-Namespace
XML-Filter-Normalize
XML-Filter-NSNormalise
XML-Filter-PerlTidy
XML-Filter-Reindent
XML-Filter-RemoveEmpty
XML-Filter-SAX1toSAX2
XML-Filter-SAXT
XML-Filter-Sort
XML-Filter-TableWrapper
XML-Filter-XInclude
XML-Filter-XML_Directory_2-Base
XML-Filter-XML_Directory_2RSS
XML-Filter-XML_Directory_2XHTML
XML-Filter-XML_Directory_Pruner
XML-Filter-XSLT
XML-Flow
XML-FOAF
XML-FOAFKnows-FromvCard
XML-FromArrayref
XML-FromPerl
XML-FXN
XML-GDOME
XML-GDOME-XSLT
XML-Generator
XML-Generator-CGI
XML-Generator-DBI
XML-Generator-Pdb
XML-Generator-PerlData
XML-Generator-RFC822-RDF
XML-Generator-RSS10
XML-Generator-RSS10-egms
XML-Generator-RSS10-ev
XML-Generator-RSS10-gcl
XML-Generator-RSS10-ipsv
XML-Generator-RSS10-lgcl
XML-Generator-SVG-ShapeFile
XML-Generator-vCard
XML-Generator-vCard-Base
XML-Generator-vCard-RDF
XML-Generator-Win32OLETypeLib
XML-Generator-XMPP
XML-GenericJSON
XML-Genx
XML-Grammar-Fiction
XML-Grammar-Fortune
XML-Grammar-Fortune-Synd
XML-Grammar-ProductsSyndication
XML-Grammar-Screenplay
XML-Grammar-Vered
XML-GrammarBase
XML-GRDDL
XML-Grove
XML-GSA
XML-GXML
XML-Handler-2Simple
XML-Handler-AxPoint
XML-Handler-Composer
XML-Handler-Dtd2DocBook
XML-Handler-Dtd2Html
XML-Handler-EasyTree-Generator
XML-Handler-ExtOn
XML-Handler-HTMLWriter
XML-Handler-Machine2GraphViz
XML-Handler-Pdb
XML-Handler-PrintEvents
XML-Handler-Trees
XML-Handler-YAWriter
XML-Hash
XML-Hash-LX
XML-Hash-XS
xml-iching-1
xml-iching-1-2
XML-IDMEF
XML-Invisible
XML-IODEF
XML-IODEF-PhraudReport
XML-IODEF-Simple
XML-IODEF-Simple-Plugin-RI_RESTRICTION
XML-IODEF-Simple-Plugin-TLP
XML-Jing
XML-Lenient
XML-Liberal
XML-LibRSVG
XML-LibXML
XML-LibXML-Augment
XML-LibXML-Cache
XML-LibXML-Common
XML-LibXML-Debugging
XML-LibXML-Devel-SetLineNumber
XML-LibXML-Enhanced
XML-LibXML-Ferry
XML-LibXML-Fixup
XML-LibXML-Iterator
XML-LibXML-jQuery
XML-LibXML-LazyBuilder
XML-LibXML-LazyMatcher
XML-LibXML-Overlay
XML-LibXML-PrettyPrint
XML-LibXML-Proxy
XML-LibXML-QuerySelector
XML-LibXML-SAX-ChunkParser
XML-LibXML-Simple
XML-LibXML-Tools
XML-LibXML-TreeDumper
XML-LibXML-xmlsec
XML-LibXML-XPathContext
XML-LibXMLSec
XML-LibXSLT
XML-LibXSLT-Easy
XML-LibXSLT-Processor
XML-Lite
XML-Literal
XML-Loy
XML-Maker
XML-Malware
XML-Merge
XML-MetaGenerator
XML-Mini
XML-MiniCity
XML-Minifier
XML-Minify
XML-miniXQL
XML-MinWriter
XML-MyXML
XML-Namespace
XML-NamespaceFactory
XML-NamespaceSupport
XML-NessusParser
XML-NewsML
XML-NewsML_G2
XML-NmapParser
XML-Node
XML-NodeFilter
XML-OBEXFTP-FolderListing
XML-Object
XML-OPDS
XML-OPML
XML-OPML-LibXML
XML-OPML-SimpleGen
XML-Ordered
XML-OverHTTP
XML-Overlay
XML-ParseDTD
XML-Parsepp
XML-Parsepp-Testgen
XML-Parser
XML-Parser-ClinicalTrials-Study
XML-Parser-EasyTree
XML-Parser-Expat-Dispatched
XML-Parser-GlobEvents
XML-Parser-Lite
XML-Parser-Lite-Tree
XML-Parser-Lite-Tree-XPath
XML-Parser-Nodes
XML-Parser-REX
XML-Parser-Style-EasyTree
XML-Parser-Style-Elemental
XML-Parser-Style-IxTree
XML-Parser-Style-RDF
XML-Parser-Tiny
XML-Parser-Wrapper
XML-Parser-YahooRESTGeocode
XML-Pastor
XML-Perl
XML-Printer-ESCPOS
XML-PYX
XML-QL
XML-QOFQSF
XML-Query
XML-Quick
XML-Quote
XML-Rabbit
XML-RAI
XML-RAI-Enclosure
XML-RAI-TrackBack
xml-rax
XML-RDB
XML-RDDL
XML-RDF
XML-Reader
XML-Reader-French
XML-Reader-German
XML-Reader-PP
XML-Reader-RS
XML-Records
XML-RegExp
XML-Registry
XML-RelaxNG-Compact-PXB
XML-Rewrite
XML-RPC
XML-RPC-CustomUA
XML-RPC-Fast
XML-RSS
XML-RSS-Aggregate
XML-RSS-Feed
XML-RSS-FOXSports
XML-RSS-FromAtom
XML-RSS-FromHTML
XML-RSS-FromHTML-Simple
XML-RSS-Headline-PerlMonks
XML-RSS-JavaScript
XML-RSS-Liberal
XML-RSS-LibXML
XML-RSS-Parser
XML-RSS-Parser-Lite
XML-RSS-PicLens
XML-RSS-SimpleGen
XML-RSS-Timing
XML-RSS-TimingBot
XML-RSS-TimingBotDBI
XML-RSS-Tools
XML-RSSLite
XML-Rules
XML-Sablotron
XML-SAX
XML-SAX-Base
XML-SAX-Builder
XML-SAX-Expat
XML-SAX-Expat-Incremental
XML-SAX-Expat-XS-Beta
XML-SAX-ExpatNB
XML-SAX-ExpatXS
XML-SAX-IncrementalBuilder-LibXML
XML-SAX-Machines
XML-SAX-PurePerl
XML-SAX-RTF
XML-SAX-Simple
XML-SAX-SimpleDispatcher
XML-SAX-SVGTransformer
XML-SAX-Writer
XML-SAXDriver-CSV
XML-SAXDriver-Excel
XML-SAXDriver-Sablotron
XML-SAXDriver-vCard
XML-Saxon-XSLT2
XML-Saxon-XSLT3
XML-Saxtract
XML-Schema
XML-Schematron
XML-SemanticCompare
XML-SemanticDiff
XML-Sig
XML-Sig-OO
XML-Signature
XML-Simple
XML-Simple-DTDReader
XML-Simple-Sorted
XML-Simple-Sugar
XML-Simple-Tree
XML-SimpleObject
XML-SimpleObject-LibXML
XML-Simpler
XML-Smart
XML-Snap
XML-Spew
XML-Spice
XML-SRS
XML-Stream
XML-Struct
XML-Structured
XML-STX
XML-Table2XML
xml-tag
xml-tags
XML-Tape
XML-Template
XML-Tidy
XML-Tidy-Tiny
XML-TiePYX
XML-Tiny
XML-Tiny-DOM
XML-Tiny-Simple
XML-Tiny-Tree
XML-TinyXML
XML-TMX
XML-TMX-CWB
XML-TokeParser
XML-Toolkit
XML-Toolset
XML-Traverse-ParseTree
XML-TreeBuilder
XML-TreePP
XML-TreePP-Editor
XML-TreePP-XMLPath
XML-TreePuller
XML-Trivial
XML-Twig
XML-UM
XML-Validate
XML-Validator-Schema
XML-WB
XML-WBXML
XML-WBXML-SyncML
XML-WMM-ASX
XML-Writer
XML-Writer-Compiler
XML-Writer-Lazy
XML-Writer-Nest
XML-Writer-Simple
XML-Writer-Simpler
XML-Writer-String
XML-WriterX-Simple
XML-Xalan
XML-XBEL
XML-XBMC
XML-XCES
XML-Xerces
XML-Xerces-BagOfTricks
XML-XForms-Generator
XML-XForms-Validate
XML-Ximple
XML-XMetaL
XML-XML2JSON
XML-xmlapi
XML-xmlapi-fixed
XML-XMLWriter
XML-XOXO
XML-XPath
XML-XPath-Diver
XML-XPath-Helper-Const
XML-XPath-Helper-String
XML-XPath-Simple
XML-XPathEngine
XML-XPathExt
XML-XPathScript
XML-XQL
XML-XSH
XML-XSH2
XML-XSLT
XML-XSLT-Wrapper
XML-XSPF
XML-XSS
XML-XUpdate-LibXML
XML-YYLex
XML_CSV
XmlActions
XMLDB
Xmldoom
XMLNews-HTMLTemplate
XMLNews-Meta
XMLRPC-Fast
XMLRPC-Lite
XMLRPC-Lite-UpdatePing
xmlrpc-pureperl
XMLRPC-Transport-HTTP-Server
xmltv
xmlwww
XMMS-InfoPipe
XMMS-InfoPipe-Playlist
Xmms-Perl
Xmms-Streamcast
Xmpcr
XMS-MotifSet
XMS-MotifSetv
xNTuples
Xorg-XLFD
XPAN-Query
XPanel
XPathToXML
XPC
XPlanner
Xporter
Xpriori-XMS
xprop2i3
XRD-Parser
XRDS-Simple
XRI
XRI-Resolution-Lite
XS-Assert
XS-boost-mini
XS-catch
XS-Check
XS-Framework
XS-Install
XS-libboost-mini
XS-libbrotli
XS-libcares
XS-libcatch
XS-libdwarf
XS-libgeos
XS-libpanda
XS-libpanda-backtrace
XS-librangeV3
XS-libunievent
XS-libuv
XS-Logger
XS-MagicExt
XS-Manifesto
XS-MRO-Compat
XS-Object-Magic
XS-Parse-Keyword
XS-Parse-Keyword-FromPerl
XS-Parse-Sublike
XS-TCC
XS-Tutorial
XS-Writer
XSConfig
XSDSQL
XSLoader
XSLT-Cache
XSLT-Dependencies
xslt-parser
XSTEST
XString
xsub
xsubpp
XT-Files
XT-Manager
XT-Util
Xtab.pm
XTaTIK
XTerm-Conf
XTerm-Util
XTM
XTM-slides
Xtract
XUL-App
XUL-Gui
XUL-Image-PPT
XUL-Node
Xul2ppt_mec
XXX
xxx2lout
Xymon
Xymon-Client
Xymon-DB-Schema
Xymon-Monitor-Informix
Xymon-Monitor-SNMP
Xymon-Plugin-Server
Xymon-Server
Xymon-Server-ExcelOutages
Xymon-Server-History
Xymon-Server-Status